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Original poster
Apr 28, 2009

Would anybody have any advice on how to alter an image to aid identification of a lost cat who is in the vet.

Images were taken inside a house in low light using an iPhone SE. I want to measure how far from the end of the paw a patch of removed fur is.

It's not clear if the cat has his paw folded under his leg or if the paw is outstrectched, because the cat is jet black, and the camera did not use the flash. There are four or five photos and a 30 sec video.

I've tried to make duplicates black and white or very light with little success using the photos app on iOS. I have no skills in this field.



macrumors 6502a
Aug 8, 2016
All colors will agree in the dark.

That said, there is no way to get any information back, that isn't or has never been there.
Solving underexposure or overexposure in a non chemical, digital generated image is where even the best digital forensic experts are struggling. Additionally there is the fact that images shot with an iPhone are compressed by JPEG algorithm and thus include JPEG artifacts, that probably makes it even harder to get some kind of useful result.

However there are tools to improve information that is still present.

I don't know which iOS apps offer them, but you could go with GIMP on a Mac or PC.
Read more in chapter 1.3.2. Exposure Problems

Work on a copy of your files and try to use
- Brightness-Contrast tool
- Level tool
- Curves tool

Sometimes it's worth working just on those color channels that are holding the most useful information.

For general reference the Histogram Dialog shows statistical information about the colors in your image.
The Pointer Dialog will show the values of specific pixels. If you move the cursor over the parts of your image that you want to improve, the values in the Pointer Dialog will give you an idea, if there is or there isn't enough difference between the underexposed areas that you can try to work on.

Good Luck!


macrumors 68000
Mar 22, 2010
Work on a copy of your files and try to use
- Brightness-Contrast tool
- Level tool
- Curves tool

In addition to those tools, you can open up a JPG of tif with the Camera Raw tool in Photoshop and have a lot of options for lightening it up while not losing detail.
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