ProPhoto RGB to CRT to sRGB – PS CS2 XP

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I have a raw image of a flower that I really like. If I load it into ACR and select space ProPhoto RGB all the detail is maintained. If I try Adobe RGB (1998) or one of the smaller gamut spaces much of the information is clipped. When I load the file into PS from ACR and convert the working space to ProPhoto RGB (from the normally used Adobe RGB (1998) the image ‘looks’ good and the histogram is shows little clipping. So my question is what rendering intent is PS using to display the ProPhoto RGB to my display and is there a way to tell PS to use that same intent when converting to sRGB for when I save for web?

Hi Ron,

It sounds to me that the bottleneck is Adobe Camera Raw’s conversion to Adobe RGB, and that you are able to successfully convert the image from ProPhoto RGB to Adobe RGB in Photoshop itself. So for web use I’d recommend that you export in ProPhoto, then use Photoshop to convert to the sRGB profile.

Incidentally, rendering intents have no effect for the matrix profiles ProPhoto RGB, Adobe RGB, and sRGB. This is misleading because the dialog allows you to select them, and nothing happens.

I’m curious about your particular image – if you can send me the raw file I’d like to take a look at it. BTW, It seems to me, from the questions you’ve been posting here, that you have really been covering all of Photoshop’s features over the last several months!
—
Mike Russell
www.curvemeister.com/forum/

Mike Russell wrote:

wrote in message

I have a raw image of a flower that I really like. If I load it into ACR and select space ProPhoto RGB all the detail is maintained. If I try Adobe RGB (1998) or one of the smaller gamut spaces much of the information is clipped. When I load the file into PS from ACR and convert the working space to ProPhoto RGB (from the normally used Adobe RGB (1998) the image ‘looks’ good and the histogram is shows little clipping. So my question is what rendering intent is PS using to display the ProPhoto RGB to my display and is there a way to tell PS to use that same intent when converting to sRGB for when I save for web?

Hi Ron,

It sounds to me that the bottleneck is Adobe Camera Raw’s conversion to Adobe RGB, and that you are able to successfully convert the image from ProPhoto RGB to Adobe RGB in Photoshop itself. So for web use I’d recommend that you export in ProPhoto, then use Photoshop to convert to the sRGB profile.

Incidentally, rendering intents have no effect for the matrix profiles ProPhoto RGB, Adobe RGB, and sRGB. This is misleading because the dialog allows you to select them, and nothing happens.

I’m curious about your particular image – if you can send me the raw file I’d like to take a look at it.

I would be very happy to send the image but I tried to post raw’s on google web albums but it converts them to jpgs and I doubt that gmail will allow 6MB attachments. I know you have a nice setup. Do you have a way for me to get you the file?

BTW, It seems to me, from the questions
you’ve been posting here, that you have really been covering all of Photoshop’s features over the last several months!

Thanks for that. When I started photography I thought it was the berries but then when I got Photoshop (mid July) I realized I like post processing way more than photography. Now I find I like mixed media more than either. Some day I hope to get a full blown vector editor.

Brgds,
Ron

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[re raw image and gamut clipping]

I would be very happy to send the image but I tried to post raw’s on google web albums but it converts them to jpgs and I doubt that gmail will allow 6MB attachments. I know you have a nice setup. Do you have a way for me to get you the file?

Gmail will do up to 10 megs, so you may be OK. Try compressing it with winzip if there is a problem. I think you know my email, but just in case, it’s mike at curvemeister.com . If that doesn’t work, I can give you an upload location.

BTW, It seems to me, from the questions
you’ve been posting here, that you have really been covering all of Photoshop’s features over the last several months!

Thanks for that. When I started photography I thought it was the berries but then when I got Photoshop (mid July) I realized I like post processing way more than photography. Now I find I like mixed media more than either. Some day I hope to get a full blown vector editor.

There’s a lot to try out there, for sure. I started in zoology, then went to computer graphics, then wandered off into video, really, before returning to still photography, and writing tools for photographers.. —

Mike Russell
www.curvemeister.com/forum/

Mike,

yes, the conversion RGB1–>XYZ–>RGB2 is executed
colorimetrically, but the result RGB2 is clipped in each channel for [0,255]. The same for the monitor preview.
Can be called Relative Colorimetric.

If the original image contains vibrant colors with
different levels in some regions, then these will appear as uniform colors on the monitor and in the smaller
RGB space, mainly in sRGB.

The monitor preview can be checked by
‘Desaturate 20%’ for different levels in the data.

If these different levels should be visible without
Desaturation, then there was probably a Perceptual
conversion applied somewhere. Right ?

Best regards –Gernot Hoffmann

wrote in message

Mike,

yes, the conversion RGB1–>XYZ–>RGB2 is executed
colorimetrically, but the result RGB2 is clipped in each channel for [0,255]. The same for the monitor preview.
Can be called Relative Colorimetric.

If the original image contains vibrant colors with
different levels in some regions, then these will appear as uniform colors on the monitor and in the smaller
RGB space, mainly in sRGB.

The monitor preview can be checked by
‘Desaturate 20%’ for different levels in the data.

If these different levels should be visible without
Desaturation, then there was probably a Perceptual
conversion applied somewhere. Right ?

Hi Gernot,

Thanks for the clarification. Yes, something interesting seems to be happening, however ACR seems to be the one that clips the colors, and not Photoshop.

It strikes me as strange that Adobe RGB would show clipping for an actual Photograph in Camera Raw. If anything I’d expect it to be the other way around, since Photoshop is more limited in its profile conversions. I’ll wait for the actual image before making any more guesses. —
Mike Russell
www.curvemeister.com/forum/

Mike Russell wrote:

Gmail will do up to 10 megs, so you may be OK.

It is on way.

There’s a lot to try out there, for sure. I started in zoology, then went to computer graphics, then wandered off into video, really, before returning to still photography

I started as an assembly language programmer (which I love best) but then got sidetracked into network infrastructure, muxes and routers and the like, and then found photography. The thing I like about graphics is that, unlike with access equipment where when I would configure a firewall the client would be grateful but they could not really see what I had done, now I can just bring someone to my monitor and show them. I know what I would really really REALLY like to do and that is 3D. I would like to be able to place cameras and lights around it a virtual room and make things come to life. This would be full circle for me since graphics demos was what I was doing when I started in assembler – AfterDark was my favorite program for years. The think about video is that it is just so darned expensive – out of my league in this lifetime.

, and writing tools for photographers..

I have looked at your Curvemeister product but to be honest I just don’t grok curves. I play around with them quite bit but it’s just seat-of-the-pants until things look the way I want them. I wanted to participate in your recent online class offering but because I have a dial-up connection figured it would be disruptive. Besides I have not short-term prospects of being able to purchase the tool so I thought it would be uncool.

Thansks as always,
Ron

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….

I started as an assembly language programmer (which I love best) but then got sidetracked into network infrastructure, muxes and routers and the like, and then found photography.

That’s funny because I started out programming a network terminal in assembler.

The thing I like about graphics
is that, unlike with access equipment where when I would configure a firewall the client would be grateful but they could not really see what I had done, now I can just bring someone to my monitor and show them.

Not only that, but your parents can finally understand what you do too 🙂

I know what I would really really REALLY like to do and that is 3D. I would like to be able to place cameras and lights around it a virtual room and make things come to life. This would be full circle for me since graphics demos was what I was doing when I started in assembler – AfterDark was my favorite program for years.

The flying toaster people? They were located a few blocks from me in Berkeley. LOL.

The think about video is that it is just so darned expensive – out of my league in this lifetime.

The probelm I had was I would spend a couple of days making the videos, music tracks, titles, cuts, etc, then no one would want to watch them.

, and writing tools for photographers..

I have looked at your Curvemeister product but to be honest I just don’t grok curves. I play around with them quite bit but it’s just seat-of-the-pants until things look the way I want them. I wanted to participate in your recent online class offering but because I have a dial-up connection figured it would be disruptive. Besides I have not short-term prospects of being able to purchase the tool so I thought it would be uncool.

Not uncool at all. The more the merrier. Many people take the class using the demo, and the concepts carry over into regular Photoshop.

Cheers, and have a good holiday.

Mike