I have another question, when opening a photo in GIMP I have to choose if I want to convert the image to the RGB working space and If I do, what type of rendering intent I want. When I want to manipulate with colors I think it is better to convert the image, but what type of rendering intent should I choose?
I fount this article: https://www.cambridgeincolour.com/tutor ... ersion.htm
Most of my images does not have intense colors, specially before edition, so I would choose to go with relative colorimetric. If I will edit some photo with intense colors, I will then use perceptual. Is it okay to start with? If you have some thoughts about this, please let me know.RECOMMENDATIONS
So which is the best rendering intent for digital photography? In general, perceptual and relative colorimetric are best suited for photography because they aim to preserve the same visual appearance as the original.
The decision about when to use each of these depends on image content and the intended purpose. Images with intense colors (such as bright sunsets or well-lit floral arrangements) will preserve more of their color gradation in extreme colors using perceptual intent. On the other hand, this may come at the expense of compressing or dulling more moderate colors. Images with more subtle tones (such as some portraits) often stand to benefit more from the increased accuracy of relative colorimetric (assuming no colors are placed within the gamut mismatch region). Perceptual intent is overall the safest bet for general and batch use, unless you know specifics about each image.
I tried to follow your steps and here is what I achieved.rjlittlefield wrote: ↑Sat Aug 15, 2020 5:25 pmHere are images that I corrected by levels adjustment in Photoshop. The way I do this is to add an adjustment layer, bring up a histogram, focus my attention on the three peaks that represent background color (which is almost everything here), then separately adjust the upper limit of two R/G/B bands so as to move the left two peaks over to match the right. Notice that in the uncorrected version there are three clearly separated peaks, one each R, G, B, but in the corrected version there's only a single peak.
I see that I also brightened the image when I color-corrected it. That's because cameras' metering expects the scene to average 20% gray, so brightfield microscopy images that are "properly" exposed according to the camera are routinely too dark.
Before color adjustment:
After:
For sure it looks closer to yours, but still something is off. Your corrected image seems brighter and less bluish. Do you have any idea what am I doing wrong?
Also I found out, that I can do this level adjusments automatically, by picking a tool called "Pick tray point for all channels", clicking on a background and it does the same thing, which is adjusting colors that RGB is a single pick on histogram.
Color adjustment by "Pick grey point".