GH1 colour space sRGB or Adobe RGB

Paul Shields said:
I'd have thought the best way to assess colour and detail from an HDV device would be to view it via the normal outputs - monitor, TV etc.
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That would tell us where in the pipeline the differences were occurring - if there were no differences then either it was being applied further downstream from the liveview or there were no differences in the first place - either. So that test would give us the those three possibilities depending on the two possible results.


I'm a photographer more than a 'videographer' and constantly have to be aware of how my images are correctly interpreted on web pages and when printing. I instinctively feel uncomfortable comparing still images shown here on a web page with what's actually output via video, but I can't explain it in the same technical depth as others here.
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I follow ya. I paid ridiculous amounts of money for broadcast monitors for what I guess are the same reasons. For some reason I feel more at ease when using the Video Toaster or the Tricasters though it's probably a false sense of security. :)

It would be great if someone could post a side by side comparison of actual footage shot with the two colour spaces. Then surely we could see it for ourselves :).
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Yeah, that might help. :Drogar-SunGlass(DBG



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e-steve said:
That video would have been better with a zombie face at the very end. :cheesy:
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Hehehe. :) Boo?
 
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That MOV just shows you don't understand how it works, you would be better off using sRGB for everything.

You should use absolute colorimetric for this conversion. With perceptual you are distorting all the colors that would otherwise be pepresented perfectly in sRGB gamut.

If (first of all try AdobeRgb instead of Prophoto, nothing displays Prophoto well really and the original was AdobeRGB in best case, right?):

a) you do an absolute colormetric instead
b) your monitor covers AdobeRGB to a good extend (wider than sRGB at least)
c) there are colors outside the sRGB gamut in the original image.

then, you would see a difference. But not in a video recording! That's impossible because the recording is limited to ITU-709. Only using your eyes, and looking at the monitor.
 
Here is a short guide:

Absolute colormetric preserves all in-gamut colors and sacrifices out of gamut colors if there are any. It makes sure you get a dependable proof on the colors your output can handle.

Relative colorimetric is absolute colorimetric that also matches the white point.

Perceptual tries to compress the gamut, so no colors will match. It's a huge sacrifice in color quality. You do get to see out of gamut colors as different (tell one from another). But, if there is none, that's useless.

Saturation simply gets maximum saturation on the primaries. There is no color fidelity, but the saturation will be maximum. Good for business use.

If you go AdobeRGB to sRGB your white point matches (D65). Prophoto is D50 though, so make sure you understand relative vs absolute colorimetric.
 
It would also help if you understood what the camera does when it captures images in ITU-709 HD. It captures the colors it can capture and clips everything else. It's an "absolute colorimetric" transform from real life to video. You are only seeing a difference because you are doing a perceptual transform which has no interest in matching colors. If you do like the blue sky better on the original though, think again, those blues were captured by an SRGB camera and you are seeing them in sRGB, which proves sRGB can handle them:)
 
Otis Grapsas said:
That MOV just shows you don't understand how it works, you would be better off using sRGB for everything.
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Below shows a clear misunderstanding of how color management works. This statement reflects that as well.


You should use absolute colorimetric for this conversion. With perceptual you are distorting all the colors that would otherwise be pepresented perfectly in sRGB gamut.
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There's usually very little difference. You would know that if you understood the LUT and Transformation matricies involved. Get some experience under your belt before you make meaningless statements such as these. Edit a few million frames as I and others have first... Or at least do some actual tests. You're robbing yourself.

Here's the same operation using Absolute.

http://tesselator.gpmod.com/Images/_Movies/PhotoshopSnapz_002.mov

If (first of all try AdobeRgb instead of Prophoto, nothing displays Prophoto well really and the original was AdobeRGB in best case, right?):
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No. Adobe and sRGB are so close to each other it's rarely meaningful to use one over the other. About 1 in 100 cases - just as I said before. It's extremely obvious to anyone who has much experience that the test image used here runs well into the upper blues of ProPhoto and beyond what AdobeRGB can deal with. Almost all RAW images from any 12-bit sensor will produce images (about one in ten on average - just like I said before) that require ProPhoto if all colors are to be used.

a) you do an absolute colormetric instead
b) your monitor covers AdobeRGB to a good extend (wider than sRGB at least)
c) there are colors outside the sRGB gamut in the original image.

then, you would see a difference.
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This is rather funny if not a little sad. I guess I'm talking to a college student? Which isn't a bad thing but like most students you have some of the information - and no idea what it means in practice - not even on a level that would be revealed by doing some simple tests (which you seem to be afraid of). You think sRGB is something big I guess? We all know how crappy NTSC is right? sRGB is less than 75% of NTSC (from memory 71.6%)! Adobe RGB is also LESS that NTSC. Every modern (CCFL) LCD is roughly about 100% to 110% of the NTSC gamut and LED Backlit LCDs are more like 112% ~ 120% all depending on model and make. Even the ancient CCFL LCDs have larger gamuts than sRGB. ProPhoto covers approximately 115% of the of the NTSC standard. WideRGB covers about 102% of the NTSC standard. ProPhoto has been in use as the defacto standard (on ANY monitor!) almost since it's inception by every professional concerned with color accuracy.

But not in a video recording! That's impossible because the recording is limited to ITU-709. Only using your eyes, and looking at the monitor.
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Yes, there is no Earth... Right?

This is kind of a waste of my time because you're using what you've read somewhere to talk out your backside. :Drogar-BlackEye(DBG Ummm, anyway I'm done with it. Let's be friends in another thread maybe. And let's continue on-topic with if, how, and why selecting sRGB/Adobe RGB is making a difference in the GH1's video. :)
 
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I explained it, I gave a link, I even explained D50 Prophoto vs D64 sRGB/AdobeRGB and then you post this clip?

Build you own reality and live in it. I have no problem with that.
 
Tesselator said:
We all know how crappy NTSC is right? sRGB is less than 75% of NTSC (from memory 71.6%)! Adobe RGB is also LESS that NTSC. Every modern (CCFL) LCD is roughly about 100% to 110% of the NTSC gamut and LED Backlit LCDs are more like 112% ~ 120% all depending on model and make. Even the ancient CCFL LCDs have larger gamuts than sRGB. ProPhoto covers approximately 115% of the of the NTSC standard. WideRGB covers about 102% of the NTSC standard. ProPhoto has been in use as the defacto standard (on ANY monitor!) almost since it's inception by every professional concerned with color accuracy.
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You clearly have no idea what you are talking about. All modern TVs comply to the sRGB standard, because they use the ITU Rec 709 recommendation. And these two share the exact same specs. The chromaticity primaries and the white point are exactly the same. And the NTSC chromaticities are also nearly the same. There is not much difference.

Here are the exact chromaticities:

Rec 709(x/y): Red(0.64/0.33), Green( 0.30/0.60), Blue(0.15/0.06)
sRGB(x/y): Red(0.64/0.33), Green( 0.30/0.60), Blue(0.15/0.06)
NTSC(x/y): Red(0.63/0.34), Green( 0.31/0.595), Blue(0.155/0.07)
Adobe RGB98(x/y): Red(0.64/0.33), Green( 0.21/0.71), Blue(0.15/0.06)

All share the D65 white point (0.3127/0.3290).

Adobe RBG1998 covers MORE colors than NTSC. You can calculate it from the above chromaticity primaries. It is about 40% larger than all the others.

And no, the "ancient CCFL LCDs" normally don't cover a larger gamut than sRGB. They often have problems even displaying sRGB correctly. Some displays have a "Wide Color Gamut" setting. So they can correctly display an image from a wide gamut source, but it just adapts them correctly to the sRGB color space. And everything is broadcast compliing to ITU Rec709 anyway.

I am not a student. I am an electrical engineer specialized in media engineering and wrote my diploma thesis about flat panel display testing. I've measured it all with a professional tristimulus meter on countless displays. Not just with my eyes or one of these cheap color measurement tools. Not sure where you've got all your information from, but it is definitely wrong. Maybe you should study some standards. I've read them all.

And Otis is also NO student, that's for sure ;)
 
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Simon Höfer said:
You clearly have no idea what you are talking about.
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:D

Hmm, OK well I'm certainly willing to admit it if I'm wrong.

Now, was't the topic here something to do with sRGB <--> AdobeRGB selection in the GH1 and it's possible affects on the video it produces?
 
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