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How can I then display/highlight some very specific points of my histogram, particularly per channels?
By @Daniel Roy
I am not sure what you mean exactly. If you want control over specific tonal levels, a Curves adjustment layer can do that. If you want to highlight specific tonal levels, a Threshold adjustment layer can do that.
Maybe we need to know more about what you need. How is the “highlighting” that you want different than the display shown in the demo below, where specific levels are highlighted?
OK that works to highlight these parts. But how can I do this per channel? I dont see any obvious way to do so. And then bonus question when I higlight red 255 for instance how can I bring those to 250 for instance.
Apologies if my questions are super naive and mis formulated...
By @Daniel Roy
No problem…Asking questions is why this community exists.
The Levels and Curves adjustment layers let you offset levels by channel. They also offer clipping previews. The demo below shows one way to set level 255 to 250 in the Red channel.
The steps shown in the demo are:
1. Add a Curves adjustment layer. I did it through the Adjustments panel, but you can also do it through Layer > New Adjustment Layer > Curves, or by clicking the Create New Fill or Adjustment Layer button at the bottom of the Layers panel.
2. In the Properties panel for the Curves adjustment layer, set it to the channel you want (or composite view for all channels).
3. If you want to preview current levels using a threshold view, hold down the Alt key on Windows or the Option key on macOS as you drag the white point or black point triangle at the bottom of the Curves graph. The reason it shows red when I do it is because this is in the Red channel.
3. Select the curve point you want to edit. You want to adjust level 255; that is the point at the end of the curve. When a point is selected, its Input (current) and Output (your change) values are shown below the graph. Note that for reference, the histogram is shown behind the curve.
3. Change the Output value of that point to whatever you want. You wanted to set it to 250. You can do that by dragging the point or editing the selected point’s Output value below the graph. Pressing any arrow key nudges the point by one level.
Even though you may not have known how to phrase the question, if this is what you were after it was a good question, because adjusting levels this way with Curves or Levels has been a fundamental Photoshop image correction technique and marketable skill for over 30 years, and therefore well worth asking about. To adjust tones between 0 and 255, you click on the curve to add a point at the Input level you want, and then you adjust that point’s Output value. In this way, you have control over up to 255 levels.
I have included a screenshot of the picture I working on and model, which is taken by Gursky. As you can see my picture's histogram is a lot more chaotic, particularly on the brighter side which I am trying to resolve.
In my opinion, part of the mystery emanating from Gursky's pictures --- this one and others --- can be found in the regularity and simplicity of the histogram distribution.
By @Daniel Roy
There may be some misinterpretation of the histogram going on here. When you describe the peaks to the extreme right and how you want to move them to the left, that is a fair goal…even without seeing the image, an experienced image editor would say that a pile-up of histogram bars at the right edge of the graph indicate blown highlights (clipping): The lightest values contain no detail. This is not good, because areas without detail are just blank. However, here the histogram stops being helpful because it can’t tell you which pixels are blown out. You have to use the clipping display to see that.
Moving the histogram data to the left is fine, except for one thing: If it is not a raw image, blown highlights may be unrecoverable that way (a solid white area has no detail to recover). If so, the optimal way to recover them is to go back to the raw image and reprocess it (or back to the original film and re-scan it) so that no highlights are blown. I am confident that Gursky takes care in his original processing to make sure highlights are protected at all steps from capture to print, like Ansel Adams would.
Proper processing from capture to print would also achieve your other stated goal, smoothing out the histogram. A spiky histogram can suggest missing levels, overcompression, and other unwanted artifacts of sub-optimal processing. The smoother histogram in the Gursky images suggests that care was taken at all processing stages to maintain realistic tonal transitions.
If the original image is raw, the tools in Adobe Camera Raw and Lightroom are built to help you preserve all the original raw tones you need, and redistribute them in any way that you need, so that you don’t have to do much more in Photoshop. In the demo below you see these steps:
1. Enable the Shadow Clipping Warning (blue) and Highlight Clipping Warning (red).
2. (optional) Enable Before/After view.
3. Adjust each of the tone controls, pulling back any time clipping warnings appear..
Notice how each option redistributes the tones:
- Exposure moves everything, but mostly the middle.
- Contrast moves the extremes in or out.
- Highlights moves mostly the lighter tones.
- Shadows moves mostly the darker tones.
- Whites changes the level at which the lightest tones are clipped.
- Blacks changes the level at which the darkest tones are clipped.
Also notice that about halfway through, I stop dragging the sliders and I start directly dragging ranges in the histogram graph, in case you find dragging the histogram itself to be a more intuitive way to redistribute the tones.
Note: If shadows or highlights are totally clipped in the raw data, then they are totally unrecoverable and the mistake was under- or over-exposure in the camera.
I believe the differences you see in the two images are partly because the photo of the Gursky image contains less clipping in fewer channels, and has smoother and more subtle tonal distribution. I also believe that the original Gursky print is likely to have much less clipping than this JPEG-compressed reproduction, or maybe no clipping at all except for specular highlights.
Conrad, I try my best not to obsess too much about colour, but I have seen some videos on Match Color
Conrad, I try my best not to obsess too much about colour, but I have seen some videos on Match Color
By @Trevor.Dennis
It’s a good suggestion, but I did not mention Match Color because the original question said “I am aware of Image/Adjustment/Match colour but looking to go furhter than that!”
I am aware of Image/Adjustment/Match colour but looking to go furhter than that!
As Match Color works destructively by default I consider it best to be avoided altogether.
Have you tried the Filter > Neural Filters > Color Transfer? (Though additional adjustments may be necessary.)
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