September 23, 2017, 07:29:19 AM

Author Topic: Histogram question regarding clipping  (Read 3926 times)

snoke

  • EOS Rebel T7i
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  • Posts: 108
Re: Histogram question regarding clipping
« Reply #30 on: August 22, 2017, 04:39:24 AM »
I knew that the develop module uses different data than the library module, as, e.g., it builds its own preview, during which at first it displays the library-module preview. I did not know, however, that it uses a different colour space and that it displayed a histogram with a greater dynamic range than the library module. I never noticed that colours and tones shift as soon as the develop module switches from the library-module-preview to its own preview. Next time I'll try to observe that carefully.

Try two monitor next each other. 100% sRGB and >99% AdobeRGB. Then you see what you don't see.

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Re: Histogram question regarding clipping
« Reply #30 on: August 22, 2017, 04:39:24 AM »

Joules

  • PowerShot G1 X II
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  • Posts: 42
Re: Histogram question regarding clipping
« Reply #31 on: August 22, 2017, 06:09:47 AM »
@sulla - for in-camera exposure, you might Google 'Canon UniWB'.
That's insanely helpfull suggestioon, thanks a lot! For non-Magic Lantern cameras and people who understandingly don't feel like trying it, that seems like a nice work around from my first little test.

I just gave it a try. I shot the blue, sunny sky at 1 second, f/1.4, ISO 100 to get a completely blown out image and used that to set my custom white balance. Works the way it should, now the Live View looks terrible but the histogram is a deal more helpfull.

I put my Rebel T3i on a tripod and aimed it at a big white cloud. I made three observations:

1) If I expose the image so that the Canon RGB LiveView histogram shows that I'm just shy from clipping highlights and take the shot, the histogram in the Image Viewer shows a great deal extra headroom, about 1.5 stops. The LiveView hsitogram is less wide than the Image Viewer histogram! They just cut away the right side! In other words, the LiveView histogram on the Rebel T3i / 600D is entirely useless for ETTR.

EDIT: Seems like additionally using the Technicolor CineStyle Picture Style reduces the difference between the Image Viewer and Live View histogram.

2) Taking shots at increasing increasing shutter speed (Longer exposure time) and looking at the Image Viewer histogram afterwards to determine the brightest exposure possible, I arrived at 1/1250 seconds, f/2.8, ISO 100. That's pretty much precisely what I would have chosen with the Magic Lantern RAW RGB histogram, which showed the clipping indicator, but without a number in it, meaning less than 1% of pixels were blown out.

Switching back to daylight WB and taking the same shot, the Image Viewer histogram touched the right border and the blinkies where on, so it thought the image was clipping even though it wasn't. Pulling back the exposure in LR, the cloud had tons of detail... I wonder if even the ML RAW histogram might not show the entire dynamic range ... a mostly white cloud isn't the best DR test subject though, is it?  ;D

3) I have yet another dust spot on my sensor  :-\ (I tried some smaller apertures before going to 2.8 )

Also thanks to privatebydesign, some more knowledge about Lightroom is very nice too. I guess I really have to look into color and the science behind it more at some point.
« Last Edit: August 22, 2017, 09:42:59 AM by Joules »

zim

  • EOS-1D X Mark II
  • *******
  • Posts: 1567
Re: Histogram question regarding clipping
« Reply #32 on: August 22, 2017, 08:20:47 AM »
Can any topic in CR actually end without insults any more..... sigh

Insults? I must have missed that. A fair bit of talking at cross purposes, which is par for the course.

yip, line was removed.
I only commented because I was really enjoying the thread, thanks to OP for posting!

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Re: Histogram question regarding clipping
« Reply #32 on: August 22, 2017, 08:20:47 AM »