The PREVIEW program does not correctly display a photo enlarged to 100% (original size)

djnail wrote:

Image for test (1210  x  1613, 72 DPI):

https://discussions.apple.com/content/attachment/6f84fb50-ab71-4407-bb76-01b152258fa7

I would have preferred a download link. Web forum software could resample if it wanted to. It didn't in this case. When I download your image, I get those same dimensions.

When I view the image in Preview and compare it to Pixelmator Pro, I see the same thing you are complaining about.

My MacBook Air 15" 2023 has a physical screen resolution of 2880 x 1864. But in the graphics engine, the screen is considered to be 3420 x 2214 @ 144 dpi. That's what I get from a full-screen screenshot.

If I open your image in Pixelmator Pro and set it to show "Actual size" then it is correct. 3420/1210 is 2.826446281. When I measure the image on the screen with my handy-dandy Free Ruler app, I can see that it is actual size. I can fix 2.82 images horizontally on the screen.

Now in Preview. The same "Actual size" image looks much larger. When I measure it with an actual ruler, it is about 9.03125 inches wide. Since this is a 72 dpi image, that would equate to a pixel size of 650. But the image is actually about twice that at 1210, which makes sense considering this is a 144 dpi display.

In fact, both images are "actual size" depending on how you measure. The question is, are you concerned about physical size or pixel size? Preview is a consumer app. It is meant for people who don't know what a pixel is. Photoshop and Pixelmator Pro are designed for people who need pixel-perfect accuracy and don't care about any physical sizes.

FWIW, I think I may know what the issue may be you're seeing. Screen shots in Monterey defaulted to 144 dpi and Ventura defaults to 72 dpi. Of course the same size image @ 72 dpi would appear twice the size of an image @ 144 dpi. You can always resample an image to 144 dpi if you like. Just to add, there is no cmd+1 shortcut in Preview, Actual Size is cmd+0.

dialabrain wrote:

FWIW, Preview has no "Actual Size" setting.

Preview's "Actual Size" setting is available from the View menu. The OP has a customized toolbar with an "Actual Size" button between the zoom in and zoom out buttons.

The most likely explanation for this is resolution. The "standard" resolution for images is 72 dpi (or sometimes 96). But when Apple "went Retina" a few years back, they decided the standard resolution should now be 144 dpi. This can cause confusion because the actual image data is the same. It is only the metadata that specifies the dpi/physical size. This usually makes a difference in Apple apps. But 3rd party apps are more likely to ignore dpi differences and just show such an image as 200% or something.

djnail wrote:

The PREVIEW program does not correctly display a photo enlarged to 100% (original size)

In standard Maс app. PHOTO - all with zoom in to actual size (100%) works well like in Photoshop.

(Bug only in PREVIEW app.)

Well I have not heard this issue before, however you can

trouble shoot further:

 —A SafeBoot Use safe mode on your Mac - Apple Support will sort many anomalies

Does a quick disk repair before it fully boots up, and certain system caches get cleared and rebuilt, third party system modifications and system accelerations are disabled.

Login and test. Reboot  as normal and test.  Caches get rebuilt automatically.

This test will tell you if third party interference; most* extensions etc are not loaded in safe boot mode. 

—Test issue in another user (or guest user) account Change Users & Groups settings on Mac - Apple Support

  This will tell you if it a universal issue or isolated to your user/admin account. 

unplug all third party peripherals when testing

Uninstall all third party apps that are Cleaners/Optimizers/VPN/Anti-Virus

all known to cause issues on the macOS

The problem is, 100% is ambiguous.

Does it mean,

• Size the image so that 100% of it fits onto the screen?
• Size the image so that one image pixel maps onto one virtual screen pixel?
• Size the image so that one image pixel maps into one physical LCD pixel?

Let's say you have a 5K Retina screen running in Retina "like 2560x1440" mode, and the image dimensions are 1800 by 1200 pixels.

If you go by the second definition, the image will occupy a 1800x1200 "pixel" area within the 2560x1440 "pixel" screen defined by the Displays {Preferences/Settings}, which will map to 3600x2400 LCD panel pixels.

If you go by the third definition, the image will occupy 1800x1200 pixels on the LCD panel, i.e., it will shrink. While this Is generally not what you want to happen in Retina modes (whose point is in part to to keep text and objects from, there may be some people on photography sites who will argue that that this is is what they want 100% mode or 1:1 or "actual size" to do.

There's a bit of an "angels dancing on a head of a pin" aspect to the discussion.

Perhaps the User ( you ) is not away and it can happen.

We are only fellow users like yourself asking questions or providing assistance to questions like this one.

Apple Is not here to read your request for a fix

Then have a few suggestions ;

1 - Get Support Choose a product and we’ll find you the best solution.Start now and open an Apple Support Ticket as they are Apple Employees to deal will these types of issues . 

2 - Product Feedback - Apple and make it known to Apple regarding this ongoing issue 

djnail wrote:

What do you think is the problem if I have two different results on my two different devices?

On one - the sizes in the programs are different,

and on the other, they are all identical

(I'm using one image in 72 DPI)

You don't seem to understand that a photo, whether digital or film, has no size.

You can display a digital image in any rectangle you want, but the pixel density will determine how "grainy" that appears just as if you enlarged a film negative beyond the resolution of your film.

There isn't a size that is 100% because there is no base size to scale from.

You may want to define 100% as the physical size that results if you display it in a frame that it fills when you display it at some reference pixel density.

Here is your image at what you are choosing to call 100% in Preview:

Here is the same image in Photos, Zoomed to 100%:

Note that I had to shrink the enclosing frame down to get to a point that I could actually zoom to 100% (and get file size small enough).

Why are they different? Because that meter isn't relative to any size. It is a zoom factor based on some arbitrary start point.

These were done on an M2 MacBook Pro with Liquid Retina XDR display.

Photos do not have a size that is independent of pixel density and display resolution. If you want to set a physical size, you must specify the pixel density you wish them displayed at to achieve that size on that display.

djnail wrote:

As I understand it, this problem will be on all new devices with retina displays ? And my iMac shows everything as I need (as in my screenshot) because it does not have a retina display ?

Well, a retina display is passé as you can see from my screenshots. The resolution is even higher, now. The original Mac resolution was 72 dpi. A retina display is double that, and the liquid retina XDR is even higher.

So, if you need one to one matching at 72 dpi, you would need a display that is native 72 dpi, or use software that provides that type of display correction.

As I explained before, Preview on Ventura defaults to 72 dpi. An image at 144 dpi displays at the same size. Here is the same result on my M1 MacBook Air, same image, same two apps. I can't explain it any better.

djnail wrote:

I'm a stock photographer more 8 years.

Then maybe you shouldn't be using Preview. It's right there in the name - "Preview". There is a reason Apple didn't name it "Apple Photo Pro".

Without opening additional third-party programs. (since this entails additional time costs)

But you're not using the 2013 iMac anymore. You can open 3rd party apps much faster on the new compute. And keep them open because the super-fast SSD also make the virtual memory system that much faster.

As I understand it, this problem will be on all new devices with retina displays ? And my iMac shows everything as I need (as in my screenshot) because it does not have a retina display ?

While I wouldn't necessarily call it a "problem". Yes. The world has changed and it isn't going back.

There really is no "problem" because there really is no "actual size". Modern computer software and hardware can handle images of virtually any size and resolution. In most cases, images can be whatever size you want them to be. The very idea of "actual size" is meaningless. Images are becoming more like vector artwork in this respect.

Both links explain the issue. If you looked at the screen shot in the one thread I provided you can see that the screen shot of the System Preference panel in Preview is the exact same size as the panel itself.

djnail wrote:

Hello.

The PREVIEW program does not correctly display a photo enlarged to 100% (original size). If you click on the scale 1:1

button (or Cmd+1), then the photo increases to 200%, not 100%!

This can be easily checked by opening this image at the same time in the Preview program and in Photoshop at 100% and compare.

Please see the example in the screenshot.

Please fix this annoying program error

P.S. in preferences checked box "1 pixel = 1 dot"

MacBook Air M1 Mac OS Ventura 13.5.1

Viewer ver. 11.0 (1044.2)

https://discussions.apple.com/content/attachment/f939a731-cc9d-456b-804f-d6e56eb7c934

Use the keyboard short cut...

Command 0 default size

Commnad + increase size

Commnad - decrease size