Novgorodets 02-05-2008 22:02

Good day to all!

It took photographs (drawings) with a resolution of at least 300 dpi. How to accurately determine the resolution? I have ACDSee 7 and Microsoft Photo Editor 3.0.
In Microsoft Photo Editor 3.0, when performing File - Properties - actions in the Resolution window are the numbers in front of Pixels / Inch. As I understand it, this is the permission? In the window in front of Pixels / Inch, you can change the numbers, thereby choosing a resolution?
In ACDSee 7, when you perform the following actions: Change - Resize - “checkbox” on Actual / Print Size in: - the “Resolution” window is activated - the required number from 72 to 600 “dots per inch” is displayed. This is also an indicator of resolution, but in this window you can set the required size?
Regards, Novgorodian.

ag111 04-05-2008 12:01

Do you know what dpi ???

Novgorodets 04-05-2008 12:42

Archangel 04-05-2008 06:54

quote: ... with a resolution of at least 300 dpi ...

dpi - density, that is, the number of dots per inch. The point on the screen and on the printer is different! Therefore, when printing, there is an increase or decrease in dpi so that the print is the same size along the length and width of the image.
By resolution, we often mean the number of points along X and along Y. For example, 1024 x 768.
Therefore, knowing the dpi and the size in centimeters or inches, you can calculate the number of points in X and Y. Well, or vice versa, knowing the printer dpi when printing and the number of points in X and Y, you can calculate the size of the printed photo in centimeters.
But why bother with this topic if the programs themselves when sending to print themselves match the dpi of the printer and the picture?

ag111 04-05-2008 07:05

Any photo can be printed with any resolution. Why define it ???

To understand the process, print a picture of 300 * 200 pixels at 1200 dpi

Knowing dpi is important when printing cards and money.

Novgorodets 04-05-2008 12:23

Thank! But alas, one of the conditions of the puzzle is precisely less than 300 dpi.

Novgorodets 04-05-2008 12:25

Thank! But alas, one of the conditions of the puzzle is precisely less than 300 dpi.

"Knowing dpi is important when printing cards and money." The second is not interesting, but rather the first.

ag111 04-05-2008 13:44

it is less than 300 dpi.

not less than 300 dpi

Excuse me, do you understand what you are writing ???

I stop all further consultations, it seems useless.

Sobot 04-05-2008 15:09

That person was pecked.
Novgorodets
It is necessary that the resolution on the computer was 2 times greater than on the printer. Those. if you want to print a photo with a resolution of 300dpi, then the digital photo should be 600 dpi
But this needs to be obtained when photographing (or scanning) if you already have a photo, then you do not need to change the resolution - you will not achieve anything with this.
Print as is and look at the result on the subject of suit-not suit. So pick up the right paper size experimentally.

Archangel 04-05-2008 15:26

Wai wai wai, some kind of fiction turned out, right up to the ridiculous. In my opinion, the author could not explain to the esteemed public what he needed. Well, at least what I understood is already explained many times, but apparently there is no satisfaction.

Kush tengri 04-05-2008 17:02

dpi - "dot per inch" - the number of dots per inch (as is customary). In a monitor, it is determined by the technical number of pixels per centimeter (per inch) vertically and horizontally (approximately 72 dpi), when printed, this value will determine the geometric dimensions of the image (if there is a picture with a size of some dots and a certain density). In order for the picture to be homogeneous and no dots to be visible on the print for inkjet printers, a resolution of at least 240 dpi is set, for laser (and printing) - 300 dpi (maybe higher). You can set the resolution in any editor (Photoshop), even in a viewer such as ACDSee, Faststone. For editors such as Photoshop, you need to go to the menu Edit-\u003e Resize and when setting the resolution you need to uncheck the "Interpolation" setting (so that the number of real points does not recount). Viewers themselves simply change the number of resolutions without touching the real points. (in general, resolution is a certain number recorded in the image profile, it does not affect anything except the size when printing).

Novgorodets 04-05-2008 22:38

Thank you dear Kush Tengri! The first normal explanation in recent times.
Task - you need pictures with a resolution of LESS (ringing, if someone confused) 300 dpi. There are pictures with different resolutions - from 72 to 300 dpi

"You can set the resolution in any editor (Photoshop), even in a viewer such as ACDSee," I have in ACDSee when - Change -\u003e Resize -\u003e "checkbox" on Actual / Print Size in: - 300 dpi immediately rises for any picture. If I set in it instead of 72 dpi (there is actually) 300 dpi - will this allow the use of pictures in printing? Same question for Photoshop.

"But you need to get this when photographing (or scanning) if you already have a photo then you don’t need to change the resolution - you won’t achieve anything.
Print as is and look at the result on the subject of suit-not suit. So pick up the right paper size experimentally. "
  Alas, dear Sobot. Experienced selection is not possible; everything is needed immediately and precisely on demand.

Kush tengri 05-05-2008 09:29

quote: Originally posted by Novgorod:
If I set in it instead of 72 dpi (there is actually) 300 dpi - will this allow the use of pictures in printing?

Yes, only the size, respectively, will immediately "leave" - \u200b\u200bit will become 4 times (approximately) less: the number of image points remains the same, only the density of their location on the sheet of paper changes.
Colleagues here promptly correctly: the first time it is unlikely that something will turn out correctly: if not the sizes, then at least the color will “float” ... you should try to do a test print more than once (if this is really for good printing).
In principle, in size: the size is 6MP from the camera (this is about 3000x2000 pixels), just at 300dpi it turns out almost A4 format (a little wider and shorter but not by much). Other formats - you can see approximate sizes right in the viewer / editor by enabling Print preview and setting “size as is” (something like “full page” and so on may turn on) - this is if the millimeters are set when resizing (when changing permissions they also change), it is not clear how it will be in real time.

300 dpi - every photographer heard about this requirement of printers for the quality of digital photo images. But how much is it really necessary? We dealt with this with one of the leading suppliers of digital images in the Russian photo market

AA: Nikita, do you believe in the magic of numbers?

N.V .: No, I'm not superstitious. But some figures have specific occupational hazards: 32 (teeth) for the dentist, 37 (years) for the poet, 300 (dpi) for the photographer.

AA: Do you have something against 300 dpi?

NV: God forbid! Welcome, we were talking about the fundamental cosmogonic constant, like the number "pi" or the speed of light in a vacuum. And this is a figure of an arbitrarily chosen board of the Ministry of Printing of the USSR. What now can be had against 300dpi, the Mongol yoke or other pages of the history of the fatherland? It has 300dpi against me!

A.A .:?

NV: As I began to print my photos, it all started right away. One day, they are calling from the magazine "Photo Store". They report that they chose my photo for the cover of the issue. But they won’t pay money, it’s enough that the honor is offered. Okay, I say, in fact, and I have enough honor. I took to the editorial staff a photo taken by the first “democratic” Canon 30D digital SLR, 3.6 megapixels.
  After a couple of days, the call: - You that slipped us, there 180 dpi!

I object that in the year before last they printed my article with photographs in A4 format made by the same camera.

Answer: - The cover is the face of the magazine, so please 300 dpi.

I object that I printed this picture on A3 for a photo exhibition and probably it didn’t turn out so bad, because I even bought this photo.

Answer: - Perhaps it is so on your printer, but we have expensive Finnish equipment, let's get 300 dpi!

I wonder what to do. An offer comes to mind - sell expensive equipment, buy a printer, and cheaply and quality will improve! But this is a conflict, and I have already bragged about the cover for someone, it's a shame.

I say: - OK, I will send you a full-format image tomorrow.

I sit down at the computer, in the graphics editor I correct the figure of 180 dpi to the required 300 dpi. With a heavy heart, I give in a pretty heavy file, because I realize that I’m a fool for a central magazine specializing in photography, and not for the large print run of Zarechye Bread Factory.

New call from the "Photoshop". I take the phone with a trembling hand. They say: - Well, that’s a completely different matter! Well, you, Nikita, yourself do not see the difference?

Yes, I say, now I see. So that I have my hands, I say, they’re dry to send 180 dpi next time! Especially for Finnish equipment!

AA: Was it long ago?

NV: A few years ago. Yes, since then magazines are used to digital technology. A familiar photographer working for Newsweek recently shared professional tricks about how he hangs a huge DSLR with a kilogram lens on his stomach, and pretending he has not started working, he quickly shoots a hot report with a compact digital soap dish hidden in his palm .

AA: And magazines no longer require 300 dpi?

NV: Magazines no longer require. But now I work in the photo bank, and the story repeats with enviable constancy, especially in the fall, when the "calendar season" is. The client wants: format - A2, resolution - 300dpi! Gentlemen, firstly, there is no such technique to fulfill your wishes, and secondly, it is not required. And then, as in a joke about a taxi driver: Gentlemen, do you have to go or checkers? If you go, then the A2 format is possible with a technically good photo. And if the checkers, then maybe it will not be difficult for you to put in the dpi column the number "300" (or any other)?

AA: You are not mistaken that such a technique does not exist?

N.V .: Let's check together. Here is a table of modern ur.

Camera			Resolution dpi
model	matrix size, pixels	price approximately
CANON EOS 10D
CANON EOS 20D
CANON EOS 1D Mark II
NIKON D2X
CANON EOS 1Ds Mark IIs

It can be seen that no one gives 300 dpi to the A3 + format (48x32cm) unless you paint them on. At the same time, only top models are included in the table, that “soap box”, which the mentioned seasoned reporter shoots for a magazine spread, we did not even consider.

AA: But there are also digital backs for format cameras ...

N.V .: Yes. But, firstly, there are 16-22 megapixels, i.e. still do not reach A2. Secondly, can you recall someone who is filming this? Thirdly, the cost of the image corresponds to the cost of equipment - 11-19 thousand dollars only for the "back"!

AA: To listen to you - so readers may get the impression that digital backs are not worth buying! But what criterion for evaluating the suitability of a photo image do you propose in this case?

N.V .: Simple. Only. And in no way connected with either 300 or any other amount of dpi. If the image looks with this format, from a given distance is good, then it is suitable, if it is bad - no.   An image may be unsuitable for a variety of reasons besides a lack of pixels. For example, shake or lightness also delights customers a little. It is not by chance that customer photo banks ask for the type and format of use, and a larger format is not accidentally more expensive. With some experience, a cursory glance is enough to appreciate the suitability of photography. If there are doubts about the quality, the image should be stretched to the required size and print a fragment of it.   If after this doubt remains, then you should pass the printed fragment to the client. If the client decides what is suitable, then it suits, if not, then it means no. The client is the highest authority, its subjective assessment is not subject to appeal.

AA: But, then a printer, or else, “Finnish equipment”!

N.V .: Well, we call for help simple common sense. The digital image is a sequence like 001011110010111010 ....

A printing device of any design does not change this sequence of zeros and ones, but only reproduces it with greater or lesser distortion. If some printing device (for example, an inexpensive printer) allows you to get a high-quality image, then this means that if someone received a low-quality image in one way or another, it is not the image that is to blame. Anyone: a drunken adjuster, counterfeit dyes, bad paper ... but not a photograph.

AA: But, polygraphists demand from the customer ...

NV: Do they require anything from Newsweek? Those involved in printing are engaged in business (printing in this case). Every normal business seeks to do the maximum amount of work for the client. But the "end consumer" is the human eye. If the eye perceives a certain small portion of the image as a point, then this is the required resolution limit. Even if it is technically possible to turn a point into a square consisting of 100 (10x10) points, then no one can appreciate the grandeur of the work done. Do you need it, does it pay?

AA: Well, let's say that you convinced me about digital photography. What can you say about the 300 dpi criterion in analog photography?

NV: But I won’t say anything. I would say, but I see no reason. No more analog photography. I recently found out from the pages of your esteemed Photonews that many foreign photobanks no longer simply accept analog photographs. The photobank I work in accepts. But we consider modern analog photos as a special case of retro photography. Accordingly, if someone wants to get a photograph of Zimny’s capture in modern quality, then I’m afraid that he will have to pay for custom-made shooting and extras.

AA: Not everyone agrees that the time for analog photography has passed.

N.V .: Not all. I respect the position “I believe, for it is absurd”. But one cannot argue with such a position by definition.

AA: Some of your statements are controversial, especially about analog photography. But here on the scales is your experience in the photobank. Let's see what objections our readers put on the other side as opposed to. I wish you success!!!

Visual acuity in humans is on average equal to 1st corner minute. Viewing a glossy magazine (or photo card) is usually carried out from a distance of 25-30cm. Then it turns out that from such a distance one can distinguish a point of order 0.073.0.87 mm.

The magic "300 dpi" means the size of the dot 25.4mm / 300 \u003d 0.085 mm. Which corresponds to the average viewing distance, more precisely 29 cm. Thus, "sculpting" smaller points or more points per unit area does not make sense - anyway, no one can distinguish them from such a distance (25-30 cm).

The angle of a "clear" vision of a person is about 40 degrees or even less. The classical theory claims that in the range of viewing angles 28-37 degrees photographs and paintings will be perceived more naturally. It turns out that from a distance of 25-30 cm it will not be very comfortable to consider a picture of more than 20 cm on the long side. When we look at a photo A4 or more (for example, A3 - at the front of the magazine), we want to move away to look around the whole image. Thus, a comfortable distance for viewing the A2 format will be at least 82 cm (with a viewing angle of 40 degrees). And from this distance the eye cannot distinguish a point less than 0.24 mm.   It turns out that on the long side you just need about 2500 points (600mm / 0.24mm \u003d 2500).

In this way, an image of 2500 or more pixels on the long side during normal viewing will look equally good in any format.   Probably not casual, 2500 is a common minimum requirement for pictures, for which 10D with its 3072x2048 pixels per eye should be enough with accurate cropping. The race for megapixels is more of a marketing nature.

Another question is that for this any format you need to be able to print the image - prepare for printing. Here the issue of sharpening control during output plays an important role - you need to consider the output method (type of printing: printer, laser, raster, etc.).

1) firstly, megapixels are different. Yes, at least compare the same D30 and a 3-megapixel soap dish. Due to the small size of the matrix (sensor), digital prints produce a noisier and more soapy image (diffraction effects affect). Here, of course, a 6-megapixel shot with the CASIO EX-P600 will lose to the CANON 10D / 300D digital SLR.

2) Secondly, on a print of A2 format, you might want to consider some small details, that is, come closer. Then a picture of 7000 points along the long side is required.

3) "The table shows that the achievement of 300 dpi is impossible even with a format larger than A4.“In principle, such cameras already exist or will appear soon. More precisely, these are“ backs, ”for example, Phase One promised to release (or has already released) P 45 in November / December. But this is a completely different conversation. Such cameras are specific and usually should be a computer and a couple of suitcases of batteries are connected, and the price they have is another 20-30 times more than 20D.

4) And of course, one must take into account the artistic value of the image - since in most cases the photo is perceived as a work of art, like a picture. Well, and the paintings, we know from what distance should be considered (see above).

   Turitsyn Andrey

What is dpi?

What is dpi? For starters, it’s nice to understand what dots per inch density (this is dpi) you want to print a picture of. It is believed that the human eye cannot see more than 300 dpi, which is taken as the basis for the standard in printing (I would say far-fetched). It all depends on how far the fingerprint is viewed, isn't it? :-) If we consider a print of high quality and excellent detail, 10x15 cm in size - from a distance of 5 meters, then you will not see any small details on it anyway! Therefore, it is not critical and the value of 150-200 dpi is for quality that is quite sufficient. Qualities rather than photographs, but viewing. And everyone will choose the distance for a comfortable viewing of prints for their own vision.

The following table shows the most common photo card formats and the number of pixels required for printing at 200 and 300 dpi. From it we can see that even a 2 megapixel camera is enough to print a normal 10 x 15 cm image.

Photo Size and Image Resolution
print see	megapixels	image size at 300 dpi	at a resolution of 200 dpi
3 x 4	0.17 MP	354 x 472	236 x 315
10 x 15	2.09 megapixels	1181 x 1772	787 x 1181 0.93 mp
11 x 15 (3: 4)	2.30 megapixels	1299 x 1772	866 x 1181 1.02 mp
13 x 18	3.26 megapixels	1535 x 2126	1024 x 1417 1.45 mp
15 x 20 (3: 4)	4.18 megapixels	1772 x 2362	1181 x 1575 1.86 mp
15 x 22	4.60 megapixels	1772 x 2598	1181 x 1732 2.05 mp
20 x 30	8.37 megapixels	2362 x 3543	1575 x 2362 3.72 mp
30 x 40 (3: 4)	16.74 megapixels	3543 x 4724	2362 x 3150 7.44 MP
30 x 45	18.83 megapixels	3543 x 5315	2362 x 3543 8.37 mp
30 x 60	25.12 megapixels	3543 x 7087	2362 x 4724 11.16 mp
30 x 90	37.66 MP	3543 x 10630	2362 x 7087 16.74 mp

3: 4 - marked formats with an aspect ratio of 3: 4 (usually used in compact cameras).

Why do you need dpi?

So what is dpi? Why is it indicated in the table? Why is it needed at all? Using dpi and the number of pixels, you can quickly figure out the approximate size of each side of the photo for printing in centimeters. So that no one would suffer, I deduced a simple formula:

where:
  x is the desired size of one side of the print in centimeters;
  r is the resolution of the side in pixels;
  d - 2.54 cm (inch);
  dpi - any desired number of dpi, for example, 300 :-)

By the way, dpi can only be a positive integer.

Example: we have a resolution of the image width of 2598 pixels, and dpi \u003d 300.
Then 2598 * 2.54 / 300 \u003d 21.99, getting 22 cm across the width of the print

Of course, neither in the table, nor in the formula did I take into account the distance from which photographs are examined (especially in connection with the individual characteristics of the view), therefore the dpi numbers are indicated as “professional” as possible. It is commonly believed: to view the print from a distance of about 30 centimeters (to see anything, say, a 10x15 photo), you need a resolution of 300 dpi. But all large shots will be viewed from a greater distance ... no one will want to look at a 30x45 cm print from a distance of, say, 10 centimeters ... Whoever doesn’t believe, be sure to try :-) you can advise printing workers who require an indispensable value of 300 dpi .

Trying to do it yourself in a graphics editor? I will tell on an example of Photoshop. We upload the photo, use the "crop" tool to make the desired aspect ratio (35 to 45), click on the "Image" at the top, then "image size", and there you will find points, millimeters, and dpi. Set the desired values \u200b\u200band click OK.

A couple of questions.
Does the image resolution depend on dpi?
The answer is no.

There is a common opinion: the more points there are in a photograph, the better it is.
  Does the quality of the photo depend on the number of notorious pixels?
The answer is no.

The resolution of images depends on the number of dots in width and height, and the quality of resolution depends on the size of the matrix, a good lens and skillful hands of the photographer.

Crazy hands are a decisive factor in most marriage cases. For example, a resolution of even 100 megapixels will not help a blurry photo, because it will still remain blurry - for any print size, any dpi and viewing distance. And then all the troubles are usually blamed on a bad camera or lens :-)

For full-color offset printing for books, 150 dpi is enough. Multi-meter posters can have even lower dpi. In general, dpi is a reference value only, or a command to the printer in automatic mode, which speaks only about the desired scale when printing. And from what distance to consider a tiny postage stamp or an advertising poster on the street, a person will decide for himself. It’s best not to see ads at all ... :-)

But in a specific shooting, dpi can be very important. For example, aerial photography for cartography. For a large map must be viewed very closely and carefully, especially for spies. Especially for spies with a camera :-)

Preparing for photo printing

Where is it better to print photos: at home on a printer, or at a photo printing kiosk? Home photo printing has the advantage of convenience and full control over the process. Disadvantages - the high cost of prints compared to photolab. But in the photo lab it's the opposite. Therefore, many people watch photos on the monitor :-)

For fans who still love to print photos, we will consider some typical cases.

Photos from digital cameras can have an aspect ratio of 4: 3 or 3: 2, depending on the camera model. Therefore, choose the appropriate paper size from the table above, or even better, find out in advance in the photo lab about the available ones.

In those cases when the aspect ratio of the image and the selected print format DO NOT coincide - we crop the image in the photo editor in the desired ratio, or ask "print with margins" in the photo lab. If they match, you should ask them to "make borderless" in the photo lab, which will help to avoid narrow white stripes along the edges of the photo paper.

A small portion of the image may go beyond cropping, regardless of the accuracy of cropping. This sad fact is related to the tolerances of printing machines on paper play. Therefore, it is recommended to place significant fragments of the image further than 2 mm from the edge. It is even better to prepare images with a margin in width and height, but not more than 50 pixels per side of the image, to compensate for paper play.

P.S. I gave only approximate reference values. And it is necessary to clarify specific tolerances among employees of a particular photo printing.

On which paper is it better to print: matte or glossy? On a glossy picture it looks brighter, but it glares great. On matte photo paper, vice versa. But no matter what you print, a bad picture will still remain bad :-)

12:36 pm - FAQ | What should be the resolution of the photograph?

So, today's question, which I am asked regularly, as soon as it comes to saving processed photos to disk:

#16   What should be the resolution of the photograph?

It's about mysterious dpi, about which customers often mention in and out of place in the technical requirements for photographs. But not everywhere else you will find this - more often in the program interfaces comes across ppi   and no dpi. And customers write and write everything "send us a photo of at least 300dpi!"   What is all this and why is it for photographers?

Short version:

In short, this is the location density:

And, most interestingly, all these things have nothing to do with digital raster photography until you are going to print it! That is, if you do not print your pictures (and now there are more such photographers than those who print), then you don’t have to bother with these parameters at all, you won’t need them.

But, just in case, in the resolution window you can set the value to 300. In Lr, for example, this can be done when exporting images, here:

For everyone else, there is a detailed answer. \u003d :)

Detailed answer:

A digital photo in a computer has only one size characteristic - the number of pixels vertically and horizontally (or their product, now calculated in megapixels). Here is this card, for example:

It has a size of 900 x 600 pixels (or 540,000 pixels, which is equal to 0.54 megapixels). The original frame from which this small copy was made was 3600 x 2400 pixels (or 8.64 megapixels) in size. And these values \u200b\u200bin pixels are the only parameter responsible for the size of photographs in digital form.

Problems can arise when you want to print a photo. Different printing machines and printers, depending on their device and the purpose of the print result, allow you to make images with different pixel sizes. That is, you can print pixels large and then on one inch (about 2.5 cm) they fit a little:

And you can play pixels a little smaller and then they already fit one inch more:

And you can make them tiny and then on the same linear inch there will already be a lot of them:

As a result, if you take and print the same image with a different pixel density per inch ( ppi), then it will have a different size on paper:

It is believed that when more than 300 pixels fit on one linear inch, the human eye is no longer able to separate them, and this gives a high-quality, "smooth" print, without noticeable pixelation. The vast majority of glossy magazines use just such (or so) print density and you can see the result yourself by buying a “glossy” printing in any kiosk.

In fact, now the density of 300 ppi is considered a kind of unwritten standard, which most publishers will focus on. Although nowhere, as far as I know, this figure in official standards does not appear. Well, let me correct, if I'm wrong.

At the same time, if we are talking about printing, for example, outdoor advertising posters (billboards) of large size (3 x 6 meters, for example), then there is no such need to make the microscopic pixels and print them tightly to each other - anyway, the audience will be on the poster look from a fair distance, not like a magazine. Therefore, very often when printing materials for such billboards, a resolution of about 50 ppi is used (there are 50 pixels of an image on one inch of a printed poster).

Ideally, you should yourself know what print density you will need and accordingly prepare your photos. If we talk about Ps, then there it can be done in the menu item Image -\u003e Image Size:

At the top of this palette, we can see the size of the photo in pixels (3600 x 2400):

And at the bottom - the size in centimeters (127 x 85 cm) at a density of 72 pixels per inch.

These 72 pixels per inch now, in general, look like a kind of spherical horse in a vacuum, because this is a purely rare indicator, which is now traditionally assigned to all digital images by default. And it has no real embodiment, because someone is now looking at the image on the monitor with a diagonal of 15 "and a resolution of 1024 x 768 pixels and he will have one image density, but someone can look at 25" from 2560 x 1600 and his density will be different. But it’s so traditionally accepted that such a figure is assigned to digital photos - 72 ppi. "The answer to the main question of life, the universe and all that - 42!"

By the way, Apple engineers knowingly described the advantages of screens on iPhone4 in such detail when they first appeared on the market. With a diagonal of 3.5 inches, the image size is 960 x 640 pixels, which gives a resolution of 326 ppi. Which, as you know, is quite comparable with the quality of a good printing printing industry. And in the future, I'm sure the number of devices with high ppi will grow steadily.

If you uncheck this checkmark:

Then you can see how the image size changes depending on the ppi density (and with a constant image size in pixels - 3600 x 2400). At a density of 5 ppi (each pixel will be printed with a square of 5 x 5 mm), the image size will be 1829 x 1219 cm:

With a "journal" density of 300 ppi, the size will be already 30 x 20 cm (almost A4 format, that is, a cover, for example):

At 600 ppi, a photograph will take on 15 x 10 paper ("a photograph, 10 by 15 with a naive signature ..."):

And at 10,000 ppi, the size of this photo will be less than one centimeter on its larger side:

It is clear that printing with a resolution of 10.000 ppi in general does not make sense, especially when you consider that the threshold at which pixels are visible is considered to be 300 ppi.

If you still want to certainly display a picture with a resolution of 300 ppi, but on a larger medium, then you will need to turn on the checkboxes again and change the image size in centimeters:

At the same time, note that the image size in pixels will also grow. This is inevitable, because you want to keep the print density high and want a larger size, which means there will be more pixels in the image. Ps will add the missing pixels, calculating them from neighboring ones. Image quality may be noticeably affected.

Well, then what is it dpithat customers like to write about in terms of image quality? This is the print density of the dots by the output device. And this parameter is purely technical, it can tell the specialist how many dots it can print, for example, a particular printer on one inch of the image.

Strictly speaking, dpi   not always equal ppi. After all, one pixel of the image must be transmitted by several points of the printing device:

Here we can see that each square (pixel of a digital image) is displayed using several circles of different diameters. Due to their different sizes, it turns out to make a different color density, and, as a result, to get full-color images with halftones on print. But the printing machine does not know how to make dots of different sizes, it can only create spots of a certain diameter embedded in the design. Therefore, the circles we see actually consist of many small dots:

The density of these dots per inch is the parameter that is denoted as dpi. And if you count, then ppi   this example is, say, equal to 25, then dpi   will be many times more.

But in modern practice, it so happened that in the quality requirements, photographers very often put an equal sign between ppi   and dpi. And come as a result of requirements like "the final image should be 6 x 3 meters at 50 dpi"that in translation into the language of digital images means that the picture should be 11811 x 5905 pixels in size. As well as requirements, like "the picture should be no more than 3600 x 2400 at 300 dpi", which, as you now understand, does not even look like "butter oil", but like "square butter." \u003d :)

Today we will dot the “i” and look at this very tricky question.

Frequently asked questions on this topic: less or more dpi? The more - the better the quality of the photo? And how does this relate to the size of the photo itself?
More and more often there is a misconception about the "quality" of images and the required 300dpi.

First, let's define what dpi is ... Dpiis a parameter that indicates the resolution of the image per inch when printing it. And then the attentive reader will think about it. Yes, yes, when printing. And until you print the image, but just look at the monitor, process it in Photoshop - dpi does not matter at all. It does not affect either the quality or the size you will print the photo (10 * 15 or A4) and generally does not affect anything. The only important parameter while you have a photo in digital form is the size in pixels. And that’s it! This is a harsh reality.

Let's look in order:

1. What if less or more than 300?
Yes, you can any number. While you are not printing, there is no difference, at least 1dpi, at least 1000dpi.

2. But what about the quality? After all, at 300 everything will be fine, as everywhere they write on the Internet, and in general this is widely heard. So, if the value is less, then the quality is worse?
As I wrote above, the quality is in no way connected with the dpi parameter. Point. Deal with it.

3. Well, what if I am going to print a photo? Then this parameter is already important and here the more - the better?
Not really. This parameter indicates how many dots (read: pixels) will be printed per inch of image. In this case, the dpi value can be set to any. For example, there is a photo sized 4000 * 6000 pixels. At 300dpi, it can be printed with a size of 34 cm * 51 cm (rounded tenths). But you can also print with a different dpi value. At 150dpi, it will be 67.7 cm * 101.6 cm.

4. And then what is the value?
It already depends on where the print is going. If in a glossy magazine, then 300dpi is quite suitable. For a home in a family album - 100-300dpi (approximately). And for a huge billboard, generally 20-70dpi is enough.
But I repeat once again - the size in pixels is more important when it comes to quality! Imagine that you have 2 photos on your computer: One with a size of 600 * 800 pixels with 600dpi. And the second is 2000 * 3000 pixels with 70dpi. Which of them can be printed more and better? It would seem that the first, he has as much as 600dpi - cool, then him! But no, the physical size in pixels is larger in the second file, despite the miserable 70dpi. The dpi parameter itself, while it is in a digital file, does not mean anything. When printing these two files, you can already select the desired dpi value. We will average it to an adequate value of 250 (you could take any number here) and get the physical print of the first file 6.1 cm * 8.1 cm, and the second 20.3 cm * 30.5 cm. As you can see, whose size is the pixels are larger - the physical size of the print is larger.

5. Where did 300dpi come from, and why is it required almost everywhere?
I don’t know where exactly the 300 number came from, but with this value, the printing house or photolab guarantees excellent print quality (considering that the size in pixels corresponds to that). In fact, this is an average figure, which may vary depending on your printing tasks.

In this photo, 2 photos are open in Photoshop. The photo on the left is 900dpi. The photo on the right is 1 dpi. As you can see, physically they look exactly the same.

If you suddenly come across a person who calls himself a professional and requires some ridiculous 300 dpi from you, without realizing what they mean - this is an ignoramus who is not worth working with. A person cannot be a professional if he needs some parameters in which he himself does not understand anything. It is better to refuse the services of such a person. Be it a retoucher, photographer, illustrator or anyone else.

And now some lyrics. For a long time I was going to write this article, but I put it off. And recently, more and more often I explain to people that dpi in the digital form of photography means nothing. Boiling up.

From real cases:
1 - The customer writes to me. Initially, there was a scan of the photo. And the output is needed, I quote: “The quality is about 600dpi, that is, a digital photo, not an edited scan .. ".
2 - In one public of retouchers, a conversation arose about how much dpi should be set during retouching ... And here is a quote from one retoucher: “They somehow wanted to force me to redo it because it was 240.”
3 - We need a photo shoot, 10 photos at the output with 300dpi.

I hope you also appreciated the absurdity of these cases ... and this is only in the last week.

On this I take my leave. Peace for everyone!