Help in understanding CO Histograms
I use a Canon 60D.
When shooting a fair number of subjects, like flowers, with a lot of red, CO shows me a histogram with what looks like blown out reds.
The histograms in the levels and curves do not show this.
The histogram that Lightroom shows me is similar to the levels and curves seen here.
Canon's DPP shows the same as LR.
Is this a bug? Something I should be worried about?
Right now, I tend to ignore it, or reduce the effect by using the Highlight slider in the HDR
While the exposure warning tells me there might be a problem, those pixels do not correspond to those on the far right of the "Histogram" curve.
Thoughts?
When shooting a fair number of subjects, like flowers, with a lot of red, CO shows me a histogram with what looks like blown out reds.
The histograms in the levels and curves do not show this.
The histogram that Lightroom shows me is similar to the levels and curves seen here.
Canon's DPP shows the same as LR.
Is this a bug? Something I should be worried about?
Right now, I tend to ignore it, or reduce the effect by using the Highlight slider in the HDR
While the exposure warning tells me there might be a problem, those pixels do not correspond to those on the far right of the "Histogram" curve.
Thoughts?
0
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The histogram tool in Capture One shows the image after adding all effects. When You add contrast in levels, curves, clarity, You will see will see blown highlights at the end of the process.
Reduce the Levels from 240 to 255 at highlights at your exaple. that should help.0 -
Interesting Jim, a question and a tip:
1. What is your current output profile in the process recipe?
2. Next, change that to a profile with a larger color space (like ProPhoto RGB) or embed the camera profile
I expect that the histogram in the Histogram tool will change but not in the Levels and Curve tool and the red channel as in your example will peak less or maybe not at all.0 -
[quote="Paul_E" wrote:
Interesting Jim, a question and a tip:
1. What is your current output profile in the process recipe?
2. Next, change that to a profile with a larger color space (like ProPhoto RGB) or embed the camera profile
I expect that the histogram in the Histogram tool will change but not in the Levels and Curve tool and the red channel as in your example will peak less or maybe not at all.
Paul,
1. Output is/ was set to srgb
2. I just cycled through all the profiles that I have - and no change.
However, something new.
I just dug deeper into Canon DPP (which I never use). The total histogram
looks ok - like the LR , and the CO levels and curves.
However, the DPP rgb histogram looks like the CO with the large line at 255 in the red
Somehow, this appears to be more a Canon 60D issue than a CO issue; though I am still confused over what is being displayed. It could just be red noise being multiplied by a large number in the rgb curve.
Perhaps I am worrying too much.0 -
clipping red colour with high saturated flowers is normal thing. You can also reduce red saturation to reduce clipping. 0 -
[quote="NNN634273366957824671" wrote:
clipping red colour with high saturated flowers is normal thing. You can also reduce red saturation to reduce clipping.
I understand what you are saying. However, it doesn't answer my question as to why the various histograms are different. Some show what could be clipping in the red, others do not.0 -
I think this relates to an issue with C1 that I've asked and made suggestions about several times, to no avail. First, the histogram makes little sense. These cameras' RAW data give 14 or 16 bits per color, not 8. Second, the internal color space of C1 is "something like" ProPhoto RGB, although I have also been told it's actually a version of LAB color. So the histogram is a composite of values that are mapped back onto a (nonsensical, unrealistic) 0-255 axis, without knowing what that axis actually represents. Second, you can't tell from this histogram when "clipping" is occurring. All you know is that there are a lot of pixels at the high end of this fake 0-255 scale -- which may be just fine, or may not be. I've been told that the reason they do this is for "usability" and "making it easier to understand for the average photographer". (I.e., it's what you are used to seeing in Photoshop.) Also note that there is a difference between overexposure (over saturation of a color sensor) and being out of gamut (not able to represent a color that the camera was able to detect or that C1 is able to infer). Hard to tell which is which from a histogram.
What we need are some actually useful and useable displays in C1, that let us see what is really going on. First, get rid of the outdated 0-255 scale; it means nothing. Second, make a clear distinction between the internal color space (hopefully a very wide gamut space similar to ProPhoto RGB, that encompasses the values of all known camera sensors within it), where the actual color values of full R, G, and B are clearly specified. Second give us waveform monitor displays that show the range of values of each column of pixels across an image -- not a count, but the actual R, G, and B values in that pixel column. Now you can actually tell when you are clipping, and where in the image it's happening, in the actual color space of the camera sensor and C1. Third, clearly indicate the difference between the camera's color space, the target color spaces and the internal C1 color space. So, e.g., if you are outputting to Adobe RGB, you might get clipping where the full C1 (and camera sensor) color space had none (because Adobe RGB is much smaller than what your camera can capture). Likewise, you should be able to see where the limits of the camera's sensors were reached, even if that is within the C1 color space. Again, this is all better done on a waveform graph or on a vector scope type display, not a histogram. Fourth, C1 should let you specify the exact color gamut of your monitor. With plasma displays and wide-gamut LED LCD displays, we can now see at least the full NTSC and Adobe RGB gamuts with very high intensity ranges, but we need to know when what we are being shown is getting clipped as well.
C1 is supposed to be a professional tool for professionals. I don't think it should be limited to conventions that Photoshop has adopted. Nor do I believe that professionals can't understand what C1 is actually doing when the highlights or shadow sliders are moved. But I think that this is why you can't tell what is going on with your histogram: you are not being given enough information to interpret this graph properly.
One more point: cameras such as the RED Epic have a base useable dynamic range of 13.5 stops, and an extended HDRx mode with up to 18.5 stops on every shot. That's from a camera that can now produce 14 megapixel still images as well as video at the same resolution. The next generation of high-res camera backs should be able to do at least as well. We have to stop thinking in terms of 8- or even 16-bit integers as being able to represent the light values that today's sensors can detect. I would hope that Phase One and Capture One would lead the way in allowing us to deal with these amazing new cameras.
-- Thomas0
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