Highlight warning

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Highlight warning

Postby NN287830UL » Wed May 15, 2019 7:14 pm

Hi All

I wonder if someone can explain the following. Just took a few test shots of the sky, the histogram on the camera is fine plenty of space on the right hand side and no highlight warning on the camera (I'm shooting RAW and realise the image displayed and histogram are JPEG based) however loading the images into capture one 12 and the highlight warning is covering a large amount of the sky as can be seen in the following image. I have also set the clipping threshold to 255

https://www.dropbox.com/s/gwxhvr9z31xz2 ... 4.png?dl=0

here is the image without the highlight warning

https://www.dropbox.com/s/m0n3olxrbx46m ... 6.png?dl=0

looking at the RGB values the blue channel has hit 255 hence the highlight warning however visually there is no loss of detail and the same images imported into lightroom have no clipping at all (no adjustments have been carried out in either C1 or LR) So I'm curious as to what is causing this with C1. I have tried both my Sony a7R3 and Fuji X-T3 with the same results.

I know I can recover the highlights with the HDR slider etc but I don't understand the big discrepancy between C1 and what LR and the cameras show.

Many thanks in advance
NN287830UL
 
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Re: Highlight warning

Postby SFA » Wed May 15, 2019 8:09 pm

Have a look at this combination.

With the Exposure warning on (note: I rarely use it) open the Exposure Evaluation tool, the Histogram Tool and the Base Characteristics tool.

In the base characteristics tool choose the "Linear Response" curve option. This is, basically, the RAW data interpreted to make an recognisable image but otherwise not adjusted so long as no tools adjustments have been applied. It may look rather flat.

Now try the other curve options to see how different the Histograms may look - although the Exposure Evaluation tool - basically an evaluation of the RAW data in the original exposure - will likely not change very much.

That may or may not go some way to giving you an explanation for what you have observed.

If it just introduced more questions that's fine because you will have seen the tools that can be useful for gaining further understanding of how processing is accomplished and someone here - someone much better qualified than I am to explain it all - will likely arrive and help you to make full sense of it all.

Part of this may be that there are special considerations for Sony and Fuji files sensitivity that I, as a Canon user, never see.

HTH.

Grant
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Re: Highlight warning

Postby NN287830UL » Wed May 15, 2019 8:19 pm

Thanks very much, Grant will do some further investigation.

Regards
Colin
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Re: Highlight warning

Postby Ian3 » Wed May 15, 2019 10:23 pm

Is it that one of the R, G or B channels is overexposed even though on average they are not? What does the colour readout say at one of the points that says it's overexposed? In Preferences, on the Exposure tab, what levels are set for the highlight and shadow warnings. (If it was rather less than 255 for the highlights, say, 245, you might get the red exposure warning even though the brightest parts of the image were short of being blown, that is short of 255.) [Edited to add - the default appears to be 250, though I set mine at 255.]

Ian
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Re: Highlight warning

Postby NN287830UL » Wed May 15, 2019 11:06 pm

Hi Ian
Thanks for the reply, yes the blue channel was at 255 causing the over exposure I had set the warning level to 255. I understand why it’s over exposed but the same image in lightroom is fine. I will try some other comparisons tomorrow.
Colin
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Re: Highlight warning

Postby cdc » Thu May 16, 2019 6:07 am

NN287830UL wrote:Hi All
I know I can recover the highlights with the HDR slider etc but I don't understand the big discrepancy between C1 and what LR and the cameras show.


Is it really a big discrepancy though? I mean just because the highlight warning comes on doesn't mean there is that much of a difference. Looking at the images in Lr vs C1 do they look all that different in the sky?

The C1 highlight warning comes on as soon as any channel reaches the threshold set, Lr is more conservative and seems to average the channels so it generally comes on later than it does in C1, in my experience.
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Re: Highlight warning

Postby NN287830UL » Thu May 16, 2019 11:07 am

I think it's just getting used to the way C1 displays the highlights, if I had an image in LR that overexposed the image would be toast, what I did in C1 was sampled the sky with the colour tool and lowered the luminance value by a tiny amount and that cleared the overexposure warning.
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Re: Highlight warning

Postby SFA » Thu May 16, 2019 12:26 pm

NN287830UL wrote:I think it's just getting used to the way C1 displays the highlights, if I had an image in LR that overexposed the image would be toast, what I did in C1 was sampled the sky with the colour tool and lowered the luminance value by a tiny amount and that cleared the overexposure warning.


If you see an over exposure warning when viewing through the Linear curve you have something to address during further processing that might be difficult to deal with.

If not .. no problems to address other than balancing the chosen curve to bring the results back into scope.

Basically, when one has got to a point of comfort working with C1, what you wrote above will give you the confidence to make use of the over exposure warning only when a small adjustment does not seem to be doing what you want ... but there are other ways you will know if you have an extreme case to deal with and you probably will not need to resort to OE warnings very often.

HTH.

Grant
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