There is usually no need to spend time playing with the image - just take a photo then do your iridology analysis.
If you are preparing posters, a book or a presentation, then go ahead and fine-tune the image but the quality is great straight out of the camera.
In some cases, if the image is a bit too dark, or was taken a little too quickly and is a bit blurred, then fine-tuning can regain some lost details.
Also with dark brown irises it is sometimes useful to increase the exposure settings, and this can be done to a certain extent to the photo after it has been taken, the video below gives further details on how to improve the image quality of a Brown Iris photo:
Mac : Photos
Windows : FastStone Image Viewer
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