How to change RGB profile using actions?

[fritz29]

We are a picture agency. We use the Adobe RGB 1998 profile in our master image files. I am using photoshop actions to size these image files for the internet. (See previous post titled Chinese Action Puzzle) In the action stream we import information into the file info and create a watermarked version of the image and more. One other step that I want to include in this is to switch the Adobe RGB 1998 to the sRGB profile. Can anyone out there tell me the best way to do this. I have tried going into preferences to make the switch but when I save the file the RGB profile is unchanged.

The reason for doing this is because sRGB is the internet standard RGB profile. Correct?

Thanks in advance.

Fritz

Fritz Hoffmann
fritz@documentchina.com



documentCHINA
An online archive of contemporary photography
documenting change in China, Hong Kong and Taiwan
http:/www.documentchina.com

[el_Brujo]

hey fritz
i use actions with a function key assigned to convert /change profiles about a million times a day, just open a file, start recording the action, go to "image", then to "Mode", scroll down to "convert to profile", choose sRGB, and then stop your action and assign a function key to it. now you can easily press your function key to quickly change from Adobe 1998 to sRGB.
hope thats what you were after.

[fritz29]

thanks for pointing me to profile to profile. I will make use of that. Cheers!

[markzebra]

Hmm you want to be careful -sRGB is a "for anyone and everyone with an 80's VDU" kind of profile. Adobe RGB tends to get used by those who's work is designed eventually for print - but its still more than adequate for screen.

Remember that the conversion process is never completely lossless.

The action should be easy enough - (using convert to profile) and you can just batch them to convert a whole folder(or use a droplet) - my advice is to keep the originalsthough

[fritz29]

I certainly can understand your concern and actually I was sticking to ADOBE RGB 1998 as the standard throughout until I recognized that the image looked very different in the browser than it did in photoshop. In fact, I can drag the image off the browser and after opening it in photoshop it matches the master file. I posed the question to a contact at Adobe and they said that the ADOBE RGB 1998 is not browser compatable and that sRGB should be used as the internet browser standard. I am only converting those images that are viewed online to sRGB. Everything else stays in ADOBE RGB 1998.

What is your point about not being a completely lossless conversion? Are you saying that by converting the RGB profile of an image back and forth contributes to quality loss? How and where is it recognized? We will only be changing the profile once in the process.

I'm still learning here so all advice is very much appreciated.

Cheers,

Fritz

Fritz Hoffmann
fritz@documentchina.com





documentCHINA
An online archive of contemporary photography
documenting change in China, Hong Kong and Taiwan
http:/www.documentchina.com

[sPECtre]

Welcome! fritz! shangai! wow that's far!

Yes, the gamut of sRGB is reduced thus going back and forth conversions will lose data.

Every conversion loses data... even going fom RGB to LAB to RGB, you lose data... check the histogram, you will see some gaps that's data loss...

A way to reduce the data loss is to work on high-bit document (for your master document)

But I'm not an expert in Color Management...

[fritz29]

Thanks for your reply. Here in Shanghai it is new years eve. New year of the sheep that is. It'll be like a war zone here tonight when everyone and their neighbor set off fireworks to shepard in the sheep.

What you say makes sense. The action I have set up makes four copies of the image for our website. The largest is a downloadable version and I want to keep that as ADOBE RGB 1998, the others are files that will be viewable when a client does their search online and these are the files that I will convert to sRGB. The key then will be to preserve the RGB profile of the master image file. That shouldn't be difficult in the action stream.

I don't think that there are any color management experts in mainland China yet. In 8 years here I haven't been able to find a one. I want to train local staff to apply color correction to raw scans using photoshop. We've been doing it now for a couple of years but I'm not convinced that we are hitting the mark and we need to expand our library staff and so I want to put together training here in Shanghai. If anyone out there can provide contact info for a color management expert whom is based here or even traveling through please pass that to me either here or by my e-mail address.

Thanks again and Gongxi Facai!

Fritz

Fritz Hoffmann
fritz@documentchina.com


documentCHINA
An online archive of contemporary photography
documenting change in China, Hong Kong and Taiwan
http:/www.documentchina.com

[markzebra]

Its snowing here in London - very beautiful, but with only an inch or so all the traffic has ground to a standstill

Yes - Sir Spectre got in before me but just to follow up what he said - no "conversion" process is completely lossless. But thats not to say its too bad really -try it for yourself a few times back and forth and use the histogram (image/histogram) to view the results. The "gaps" may still not be visible to the eye though.

The reason images look different in the browser is because the browser (probably IE - lets face it - it always is these days) uses sRGB to "filter through" the images for on-screen use in an attempt to make sure everyone sees the same thing!

From the way you have set up your files - it doesnt sound too much of a problem though. As youve said - the sRGB's are just for thumbnail on-screen use anyway.

Actually - I'm assuming your compressimng the images as Jpegs - thats much more likely to degrade the images than anything else