SRGB vs RGB 1998

I think you mean sRGB -v- aRGB?

To cut a long story short, aRGB is capable of handling more colours than sRGB, but thinks will look darker if you're using a program that doesn't understand aRGB to view them.

If you're using something like Photoshop (which understands aRGB) then it displays it just fine.

"...(which understands aRGB) then it displays it just fine"

Actually, if your using a color-managed application then an sRGB and Adobe RGB image should look the same. They will look different in non-color-managed applications (like most Windows web-browsers). In the latter case, sRGB is closer to the run-of-the-mill PC display, so it's usually better to save anything that you're making for the web as sRGB.

seriously i'm ready to fall on a knife or stick needles in my eyes when it comes to "color management"....i'm definitely talking about "srgb" vs "adobe rgb 1998" when using lightroom i have these options when i export....one lab i use wants them in "srgb" so i noticed that srgb has more color than adobe rgb 1998 and according to what i read srgb is a smaller color space. so i'm very confused - can someone please break this down for me???????????

Oh Boy ... here we go ... :)

RGB stands for Red, Green, and Blue - the three primary colours that we use to make up our images.

So - if you were to peek inside a photo file you'd find that a particular pixel might have a R(ed) value of 123; a G(reen) value of 231, and a B(lue) value of 23 - unfortunately, although we know "how much red", "how much green" and "how much blue" to use for this pixel, we don't know what shade of Red, green, or Blue that we're talking about - if the shades of red, green, and blue that your camera uses is different to the red, green, and blue that my monitor uses then what I'm going to see isn't what the image is supposed to look like.

So ... we need standards - standards that define "what shades of red, green, and blue" were talking about - and that's what sRSB and aRGB 1998 are - different "shades" of colour. So to correctly describe an image you need a couple of things - firstly you need "the numbers" then you need a "standard" (called a colourspace) that defines what the numbers mean.

It's a bit like me typing an eMail in English - and then sending it to someone in Italy who assumes that what I've written is in Italian - and because of this the meaning of the eMail changes. If I'd written the eMail in English and sent it with a big post-it note attached that said "written in English" then all would be sweet.

So - if you capture an image and save it in aRGB format, and then dislay it or print it on a device that's expecting sRGB then the image won't display correctly - in general it will be darker with more subdued colors.

To explain why it looks darker when aRGB has more colours ... think of a single red pixel - that pixel under sRGB might have a value of 200 (out of 254) - but because aRGB has to allow for more colours it has to be more conservative in it's numbering (because 254 is still the limit) - so in aRGB that same red pixel - at the same level of brightness might only be given a number of 175. Now when you display that (aRGB) pixel in a prgram that thinks it's a sRGB pixel all it sees is a pixel that's 175 (not 200) - so it displays it dimmer.

To be honest unless you're a glutten for punishment, don't worry too much about it - just work in sRGB and you won't go too far wrong.

You might be wondering why they have these different colourspaces (there's even bigger ones like pro-photo and LAB) - the basic problem is that the human eye can see a certain range of colours - cameras capture a different range - and printers print get a different range again - sticking to a small colourspace like sRGB keeps you out of trouble (it's pretty much just the lowest common denominator), but cuts down on what might have been possible - the flip side of the coin is that other spaces like LAB are cabable of describing colours that we can neither print nor display - and it's possible to get oneself into all kinds of trouble if one doesn't know what they're doing.

Hope this helps - just let me know if you need more help and I'll try to expand on it some more for you.

Cheers,

Colin

Meg, I also got sick of all the geek talk about color management. It's all true, but I really don't give a darn ... I just want to get what I'm seeing on the monitor on a print. So, for my pea brain I simplified it all ...

1) calibrate the monitor. I use the Mac calibration for my 23" cinemas. At the end of the calibration process I can assign a name to it, send that calibration to be saved in the list of color profiles.

2) In Photoshop I go to >Edit in the top menu and scroll to >Color Settings, then select that same color profile that I named as my Monitor working space from among all the profiles in the list.

3) with a image open in PS, go to > View in the top menu and select >Proof Set Up > Custom ... and select that same profile from the drop down menu. Once you select that, it'll stay until you change it.

4) When sending prints to my home printer, I select that same profile in the printing dialog box and let Photoshop determine color NOT the printer.

5) If sending for external prints or for on-line proofs, I batch CONVERT to sRGB. Convert attempts to keep the same relative color appearance. If a printing lab has a specific profile they want you to use, it gets loaded into the profiles, and you CONVERT to that profile instead of sRGB.

The key is what you are seeing on the monitor is what you get in the print ... so it just made sense to me to use the monitor profile in every place there's a choice. The CONVERT option is suppose to do exactly that ... interpret the colors you see to a different color space, not change them.

I know I'll get ripped apart by the geeks, but it works for me whether printing on my home printer or from a lab. Even when I've done a match print at home and brought the same image to a lab, it usually matches.

Hi Marc :)

You were doing well until you got to #3 - this is where you're setting up the soft-proofing so that you can simulate how it's going print, but on your screen rather than waste paper and ink.

For this bit you should select the profile for your output device (ie printer). If you get away with it most times then great, but if your trying to soft-proof something that has vastly different tone characteristics (like canvas) it'll bite you in the bum if you make changes to get the softproof "looking right" (like dark greys of a grooms suit) - if you don't soft-proof (and usually there's no need to) then it doesn't make any difference.

In step 4 you should also be selecting the correct profile for your output device - by selecting a monitor profile as your output profile the degree to which it matches is proportional to the degree to which your printer behaves like a monitor (from a colour management perspective).

Unless you are using a stupidly expensive screen, and as far as I know there are only 2 of them, you won't be able to see more than sRGB on screen anyway. I hope this answers your original question.

Colin, I don't select the output device profile, I tell the print dialog to let Photoshop select the colors in the "Color Handling" drop down menu. Since I selected my Monitor profile as the proof profile, it automatically is that profile that PS is using. Under "Print" both the Document and Proof options are the same profile... so it doesn't matter which is selected, it's the Monitor profile that is converted to the printer color space. Since I'm sending prints to two different printers (Epson 2400 and 3800 ) it's always the same ... the same photo sent to both printers matches ... which I tested to be sure. Seems to consistantly work. BUT I do select which paper I'm using when printing.

Profiles fall into two categroies - device independent and device dependent.

Examples of device independent are sRGB, Adobe RGB, Pro Photo RGB, etc - these are also referd to as working spaces for images. Some of these are able to represent a wider gamut of colors, and each has a fixed definition of how to represent colors.

Examples of device dependent profiles are monitor, printer, scanner, etc. These are profiles for a specific piece of hardware (either an input or an output device). Printer profiles are specific for the printer with a specific ink and paper combination - you need one for each paper and ink conbination for that printer. Monitor profiles are specific to your monitor and are not adequate for any other monitor (if you want accurate color).

You should never assign a device dependent profile (monitor or others) as your working space for image editing software. You should select a device independent profile (sRGB, Adobe RGB, etc) for your working space. Photoshop automatically selects the current active monitor profile and uses it to modify data sent to the monitor so it displays color correctly. Some software requires that you select a monitor profile so it can use it to modify data sent to the monitor to display color correctly.

Software that displays images can be either color managed or not color managed. Color managed software reads the embedded profile of an image (assuming it was embedded) and uses it to modify data so it displays color correctly. Photoshop is color managed, so an images with sRGB, Adobe RGB, Pro Photo RGB, etc will all appear the same on the monitor. Non color managed software (Windows Picture and Fax Viewer, the internet, and most others) will only display sRGB correctly - others will appear flat and low in saturation.