sRGB VS RGB

[EOS_JD]

Originally Posted by pop

Jfrancho;
Although only mentioned briefly. I do my own printing. I work in RGB mode shot from raw in PS. I just make sure that my printer ( in this case EpsonR350 ) is also set to print in RGB. The same is true if working in sRGB. Set your printer to print in sRGB.

How do you set your printer to print sRGB? Are you setting a profile? If so this is probably wrong. Your printer natively converts the info in your RGB image to output using it's own colors. Mine uses 8 colours.

In setting a printer profile, it should be specific to that printer (ink)/paper combination. Don't use monitor (icm) profiles or an image profile for your printer. Printers use icc profiles and manufacturers of your paper provider will generally have appropriate profiles. e.g. I have an Epson R2400 and print many images using Ilford Gallerie Smooth Pearl Papers. To get the profile I go to the Ilford site and download the profile for that printer/paper setup. download the IGSPP9_EPR2400_PSPPN.icc and install that. You are then able to select the appropriate profile so that your image should match the screen. Much of this relies on having a properly calibrated monitor though.

When you say you work in RGB there are a few RGB profiles. I use both adobe RGB (aRGB) and sRGB. I set my image colour space to aRGB if I want to print it and sRGB if I'm saving for the the web.

My printer (Epson R2400) though gets the appropriate profile for the printer/paper.

[pop]

EOS_jd
Agree with what you say....and apologise in that I did err...My printer has the option for RGB but not sRGB...This is set in PS....For me, I always leave all settings in RGB and I am happy with the result.

[trixiebell]

Just wanted to come in and thank jfrancho for all the help on this thread....it has helped me tremendously in understanding!
Thanks so much!

[MrB]

Very thorough, J Francho

[jfrancho]

Originally Posted by pop

Jfrancho;
Although only mentioned briefly. I do my own printing. I work in RGB mode shot from raw in PS. I just make sure that my printer ( in this case EpsonR350 ) is also set to print in RGB. The same is true if working in sRGB. Set your printer to print in sRGB.

Device profiles and colorspace profiles are two different things. Colorspace profiles describe the gamut of color available and how it is stored in the image file. A device profile describes how to display or render that color data on a specific device. Monitor profiles and print profiles are device profiles. Adobe RGB (aRGB) sRGB, Prophoto RGB, etc. are colorspace profiles.

[kidnanrud]

Thank you so much. I have been confused about the camera settings for landscape, people, etc. You have clarified that issue very well.
kidnanrud

[mjdl]

Links to one particularly clear and well illustrated set of not-too-long tutorials about color management can be found at Digital Photography Tutorials (lower part of the page).

People have touched on most of the main ideas in this thread. I'll just add another way of looking at your choices of color space: given that there can only be a finite number of colors when encoding the actual colors of the scene in an 8 bit/channel or 16 bit/channel RGB file, you want to choose the color space that is likely to adequately cover all the gamut of natural colors your camera's sensor can record.

Choosing a color space that is too wide means that a portion of the encoded color space is never really going to be used, since the "extreme" colors are seldom (or cannot be) recorded by the camera sensor, leaving fewer RGB numbers to encode the "normal" gamut (and if there are too few left, that may be observed in gradients, such as intense blue sky displaying color "banding"); choosing a too narrow color space means that some of the natural gamut of colors will be artificially compressed into the gamut of the smaller color space.

For editing and archival purposes, i.e. doing post-processing work and saving it for future use, you want to choose a space that efficiently encodes without losing gradations and extreme colors that the sensor was able to record. Most dSLRs using Bayer format sensors record 10-14 bits per R, G, or B sensor site, and the raw converter then interpolates the corresponding RGB pixel value from that sensor site and the 8 other sites surrounding it; the actual color that RGB pixel maps to to depends on the color space. Hence the recommendation to edit and save the output from camera raw sensor converters in 16 bit/channel format and a wide color space that covers the sensor's entire range.

So, in terms of preparing files for output: a file destined to be printed on a high quality photo printer can be usefully encoded in a wider color space than one that will be displayed on an average LCD, since the print can display a wider gamut of colors than the LCD.

Thus the usual recommendation for print output with maximum use of the printer's potential gamut, is to do most editing in a moderately wide color space like AdobeRGB and, if there's any risk of banding, to edit files in 16 bits/channel format. You can always convert the image data into the smaller gamut sRGB color space and 8 bits/channel for web purposes later.

Needless to say, there's no reason to go crazy thinking about all this: most of the time the sRGB working color space and 8 bits/channel is perfectly adequate for most usual post-processing in digital photography; shooting raw format is just a way of keeping all options open, as is the use use of a wider AdobeRGB working space and 16bits/channel for post-processing and archiving the result. You can do comparisons on a photo by photo basis and see how the choice affects your work.

[blumesan]

@mjdl

First of all WELCOME TO THE CAMEL. I hope you will find a home here where you can both contribute and learn.

Thanks for your first post. It is informative, cogent and extremely well written. Look forward to reading many more such posts from you.

Cheers/Mike

[kidnanrud]

Thank you mjdl......the following is something that I had no clue to and was very helpful.
"Choosing a color space that is too wide means that a portion of the encoded color space is never really going to be used, since the "extreme" colors are seldom (or cannot be) recorded by the camera sensor, leaving fewer RGB numbers to encode the "normal" gamut (and if there are too few left, that may be observed in gradients, such as intense blue sky displaying color "banding");"

[mjdl]

If I haven't already given a hint that I'm really a beginner in digital photography, this is probably the time to 'fess up to that!

Trying to give others a coherent explanation of aspects of what I find a somewhat confusing topic--color management--is a good test of whether I've really understood it myself, so I'm grateful to the thumbs-up and encouragement.

I guess I could sum up my first post above to: if the original scene includes a very wide range of colors and contrast critical to the success of the final picture, or there is going to be a significant amount of post-processing, then selecting a wide working color space and as much bit depth per color channel as the editing software allows ensures that the least amount of image data captured from the scene is lost in the final result. (There will always be some losses, depending on the form of the output.)

[NikonMarty]

hey, another Canuck
welcome mjdl..

back on topic (Marty gives his head a big ol' shake )
damn this is a lot of info to digest and me thinx it's gonna take me a while to work thru it

couple of questions off the top of my head tho;
why, when exporting from LR to CS3 do i have to convert to either a tiff or PSD? weird but don't they both work in RAW?

re: "save for web or other devices"
any idea why i'd be getting converted files going to the reddish side? all images get a reddish tinge to them..

tia
M

[mjdl]

Originally Posted by NikonMarty

hey, another Canuck
welcome mjdl..

Thank you!

Originally Posted by NikonMarty

why, when exporting from LR to CS3 do i have to convert to either a tiff or PSD? weird but don't they both work in RAW?

I don't use Photoshop, but don't some versions have "Smart Objects", which allow embedding a raw file (with all the user-selected ACR processing parameters) in a PSD? That would certainly reduce the number of intermediate files while you are working on a particular photo. Once you've reached your desired final result, saving it as a single layer PSD or TIFF makes sense just to save space (even more so as a 100% quality JPEG, if you are absolutely sure that no further editing/resizing is required!).

What Lightroom seems to do (again, I don't use it, so I'm guessing here) is store the raw file (which is not editable in any conventional sense) and all of the raw editing parameters the user has chosen, giving the illusion that a raw file has been "edited"--the edited version can be saved in whatever output format you choose.

A really good explanation of the digital image processing pipeline from sensor data through raw to JPEG image can be found at Sensor Processing Pipeline (In fact, all the digital technology articles of Rags Gardner at Rags Int., Inc. Digital Photography are worth carefully reading.)

Originally Posted by NikonMarty

re: "save for web or other devices"
any idea why i'd be getting converted files going to the reddish side? all images get a reddish tinge to them..

No idea; maybe this is a consequence of mistakenly assigning or converting an image to a monitor color profile instead of a working space profile.

The only way to get things working right is to work it through, factor by factor:

1) if you have a calibrated and profiled monitor, make sure that your Adobe products are configured with the correct profile, and if you don't have such a monitor profile (or even if you do!), visit a LCD monitor test site such as LCD monitor test images and get a good idea of how your hardware currently displays image tones (shadows, highlights, gradients, neutral grays, etc.). Try to correct any obvious deficiencies of your hardware first.

2) Get an idea of how your workflow and system deals with color management and its effects on the image:

Using Lightroom, ACR, or Capture NX, edit a photo that has a nice selection of shadows, hightlights and middle tones such as skin--such that your eye will easily recognize any contrast deviations and color casts when the photo is displayed by other programs.

Save that photo a) as a 100% quality JPEG in the sRGB color space (making sure that the sRGB color profile is embedded in the file--refer to the options in the Save dialog) and b) in the sRGB space but *without* embedding the profile, both at a size that fills most of your monitor screen but that allows all the programs to display it at 100% size (no resizing, in other words).

Then open those JPEGs in color-managed programs such as Photoshop (if it does not ask you how to color manage the JPEG without an embedded profile, then Photoshop is misconfigured) and the Safari browser, and, if you are on the Windows platform, non-color-managed applications like Internet Explorer, Paint, or Windows Fax and Picture Viewer.

They should all display the JPEGs in an almost identical manner (there may be very slight differences between them, but nothing that you'd call an outright color cast or change in overall gradation).

If they don't, then there's something wacky going on, and unfortunately I'm neither knowledgeable nor experienced enough to help, but these are, in any case, the kind of sanity tests that you should perform to make sure that the processing workflow deals with color correctly.

(A really common oversight for Photoshop users is to edit in a wide color space like AdobeRGB and then use the "Convert to Web" feature to quickly produce JPEGs, forgetting that unless explicitly configured otherwise, that feature does not convert the image data to sRGB, giving those anemic faces and desaturated colors you sometimes see on Flickr.)

[blumesan]

Originally Posted by mjdl

If I haven't already given a hint that I'm really a beginner in digital photography, this is probably the time to 'fess up to that!

You may describe yourself as a "beginner" but I suspect you are being overly modest. However, as your posts demonstrate, you certainly deserve kudos (and karma) for the clarity and precision of language in communicating what you do know. Unfortunately this is an all too rare skill which, I find, is disturbingly deficient in many of the more experienced (more prolific?) posters to this forum.

Keep up the good work.

[NikonMarty]

thanx mjdl..

i'll have a look at the settings because this problem is evident straight thru CS3
editing and save done thru it alone
image is edited in raw format and then off to "save for.." i go
i use the split screen setup and i can see right there that the problem exists, so i'll run with your theory that it's a "to sRGB" conversion issue first and see where that takes me

much appreciated!!!!!

and i completely agree with blumesan

[heymirth]

This is what I get when I save my jepgs as RGB vs Srgb. For months I was wondering why my images on my blog look bad, I thought it was my monitor at work

WOW what a difference

RGB






SRGB

[EOS_JD]

Originally Posted by heymirth

This is what I get when I save my jepgs as RGB vs Srgb. For months I was wondering why my images on my blog look bad, I thought it was my monitor at work

WOW what a difference

RGB






SRGB

The web is suited to sRGB images. For printing, aRGB has a larger gamut.

I save web images as sRGB but for printing I use aRGB

[JohnGalt_ny]

This thread is HUGE.

JFranco, thanks a ton for actually getting me to understand this stuff.

I'd kiss you but you'd probably prefer this Karma.

[sirbridge]

I agree but what interests me more are the two pictures on the wall. Were they taken by you and what flowers are they ?

[rjalex]

Originally Posted by Eero Makela

From what I understand of RAW it does not have a color space setting. Yes it may have a default based on camera setting when you open it in a program that is aware of the RAW format. But the RAW file has the largest gamut of colors possible and all you need to do at the end of the processing is to decide what you convert it to. sRGB for web.

Hi Eero,
thank to all participants in this interesting thread.

To make things confusing, in my Canon 40D menus you can setup the color space ONLY if you are using one of the "advanced" modes which in my camera are set to produce RAW files !

If you use one of the "beginner" modes (potrait, sports etc.) the setup menus are greatly simplified and you CANNOT setup the colour space !

confused

Take care
Bob

[jfrancho]

Originally Posted by rjalex

To make things confusing, in my Canon 40D menus you can setup the color space ONLY if you are using one of the "advanced" modes which in my camera are set to produce RAW files !

If you use one of the "beginner" modes (potrait, sports etc.) the setup menus are greatly simplified and you CANNOT setup the colour space !

confused

Take care
Bob

You should be able to set color space to sRGB or Adobe RGB, irrespective of shooting mode. See p. 74 in your manual for details. I recommend early binding to sRGB, if you are shooting in the basic shooting modes. That way, they are web ready, right off the card.