Cropping: Square not always square

I need my square crops to be exactly square. They’re not always square, as can be seen in the screenshot. I have to play around with the cropping tool and observe the dimensions.

macOS Monterey 12.7.5 / DxO PhotoLab 7 7.7.1 / 25" monitor (2560 x 1440 pixels)

Get a square square by dragging a corner, then move the whole frame to position the crop.

Strange. Mine have always been square. I’m on Windows. Maybe the issue is related to the Mac version.


But I still do have to drag a corner until I see that the dimensions are correct.

Yes, most of the time it is correct. I only notice the problem once I’ve uploaded an image to Flickr, and an admin rejects the photo I added to an ‘Only Square Images’ group.

I could reproduce the problem on PL7/Win.

  1. Select manual crop with aspect ratio 1x1 somewhere on the side of an image with strong barell distortion.
  2. Close the crop tool.
  3. Apply distortion correction with ‘Keep aspect ratio’ OFF.
  4. Open the crop tool to check for non-square dimensions.

Not always this problem is reproducible. In particular I couldn’t reproduce it, if ‘Keep aspect ratio’ was selected, or when distortion correction was applied while the Crop tool was active. Sounds like a feature, rather than a bug. Just don’t use the Crop tool before Distortion correction is applied, sort of logical way to do it.

I will test that.


I’ve used Z8 (8256 x 5504) with Z 24-120/4S at 24mm – this lens is known for high barell distortion at wide angles. Square crop was near the corner, but far enough from the edges, so that it didn’t got cropped by distortion correction, with size about half of the image height. Starting with 3037 x 3037 square, closing the crop tool (seems to be an important point) and applying distortion correction with ‘Keep aspect ratio’ OFF (also important to get a false square), resulted in a 3093 x 3037 crop.

However, if I do it in a logical way, i.e. apply distortion correction first and crop later, the 1x1 crop is always a square.

For every lens of mine that has a profile, lens distortion correction is automatically set when I open the file via my startup preset. I will test by selecting the no corrections preset first then I will create a square crop in an area most likely to be affected by the distortion correction, and finally I will add the distortion correction to see how it affects the size of the one-to-one crop.


@Wlodek , if crop dimensions are managed in % of image dimensions, it is to be expected that the ratio can change with distortion correction, as this can stretch the image differently for horizontal and vertical dimensions.

Sure, that’s why I thought that OP problem has something to do with Crop and Distortion interaction. The “problem” does not happen, when (a) distortion correction is applied before cropping, or (b) distortion corr. is applied while the crop tool is active, or (c) ‘Keep aspect ratio’ is selected. The only “bug” is that when you get non-square “square” as above, the Crop tool still displays 1x1 aspect ratio, rather than ‘Custom’. But this is a minor issue, which appears only due to user “error”, so not worth bothering, imho. Let’s see, if this explains OP problem, maybe it was something different – too few details there to judge.

I tested cropping a square before applying the distortion correction and then added the distortion correction to it. The dimensions were identical and did not change as a result of adding the distortion correction before or after the crop.


Interesting. Maybe you had ‘Keep aspect ratio’ selected, crop tool was active when applying distortion tool, or lens was free of distortions (can it happen?). I could reproduce it on two photos taken with with Nikon Z24-120/4S @27mm on Z8 and AFS 14-24/2.8G @14mm on D700.

EDIT: Actually I had trouble reproducing the behaviour with AFS 14-24/2.8 @24mm on D700 (12 mpx), because the lens distortion was almost non-existent at that focal length.

I had lots of lens distortion. I tried it on several different images and also tried it with the perspective tool, While the width and height pixel count value changed when using perspective, they were still always identical to each other.


A problem since ages ago.

I have complained to DxO multiple times. It persists several major versions of the product later.

You may find your crop says something like 1000 x 1001. Whatever you might use to try to rationalise this, it is completely possible, always, to make it say 1000 x 1000. You just have to drag it in different ways until they are equal.

Produced by dragging until I saw a mismatched pair.
CleanShot 2024-07-10 at 20.23.58@2x

Then by repeatedly dragging the same corner until it matched.
CleanShot 2024-07-10 at 20.25.05@2x

I did note that it was correct far more often than not, which is an improvement on how it used to be.

Known as floating point rounding errors, these are notoriously hard to avoid. Trying to match one number to another can end up in a recursive loop where altering the first leads to a change in the second, which then provokes a need to change the first.

But, think about it… we are talking about a 1px difference. At printing resolution of 240ppi, that equates to 1/240 of an inch, which is never going to be discernible to the naked eye.

Then I would suggest that the group’s admin do not understand about rounding errors :wink:

@Joanna I think, this is the important part:

If height and width are not equal, even by only one pixel, they’re not a square.

@FrancisM You not only have a lens distortion correction active, bud additionally also a perspective correction. If Photolab is incapable of squarish output, use a pixel editor like PS or Affinity Photo afterwards.

I defy anyone to be able to determine whether 1px makes a real visual difference without zooming in and pixel counting.

My guess is, the admin was using a little macro to check if the image is allowed or not and it could have been more than one pixel in the case @FrancisM was talking about.

Fact is, PL is not reliable on that part.

Fact is, when the speedometer in your car shows 50km/h, what exact speed are you doing?

Does that make your car any less reliable?