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Should I use sRGB or Adobe RGB Color Space?
by Zenon Char
The Purpose of This Article
The intent of this document is to help people new to digital photography understand
the basics of color management. It has two purposes. First to help you decide
if you want to use sRGB or Adobe RGB color space. These two are the most common
color spaces and there are pros and cons to both. Second if you choose Adobe
RGB you must know how to manage the color space for web viewing and printing.
It has been stated that if you have no specific application to use Adobe RGB,
stick with sRGB. There is nothing wrong with sRGB as it can produce great color
and is easier to work with if you don’t want to get involved with color
space issues.
There is much more to this so read on as I also cover the following topics.
sRGB stands for Standard RGB. It was developed by Microsoft & Hewlett-Packard
and most of the planet is geared for it: monitors, printers default settings,
the equipment that develops your prints at Walmart, etc. Adobe RGB was developed
by - you guessed it - Adobe “to encompass most of the colors achievable
on CMYK printers (see Visual 1), but by using only RGB primary colors on a device
such as your monitor. Adobe RGB was designed for the commercial market. I will
refer to it as aRGB from this point on.
I work in the printing industry - printing as in printing magazines, rather
than printing as in photography. The pre press (designing) department works
with Photoshop on the monitor, which is in RGB. When done, they convert to CMYK
to produce the printing plates that will be installed on Cyan, Magenta, Yellow
and Black printing units so we can print magazines that you buy at the store.
If you choose to use aRGB for non-commercial applications, the simple rule is
that for all normal photographic printing purposes you should just select the
print command and let the printer sort out how to use the inks at its disposal.
You control this through the color management facilities in the software you
are using (profiling your printer). Do not try to do the CMYK conversion yourself.
Visual 1
Does your printer look like this?
Let’ go back to the basics. Humans see all color in RGB light waves:
Red, Green and Blue. sRGB and aRGB are not separate entities. They both fall
under the RGB Color Spectrum. Humans can see all the colors within the entire
color spectrum or that entire color area you see in Visual 2. No camera or monitor
can see it and no printer can print it.
NOTE: If you want to learn more about RGB read “Color Theory,
White Balance and RAW” which can be found at Digital Image Café.
Visual 2
Let’s look at the sRGB color space. Imagine crayons standing on end,
tightly packed within the sRGB color space area. If you want to use the aRGB
color space you don’t get more crayons, they spread out. The advantage
is that on the outer edges of the aRGB color space you start to capture more
color. Now there are spaces between the crayons however Photoshop does a great
job filling them in.
Color space is also known as Gamut. Gamut - a certain complete subset of colors.
There is a misconception that aRGB will yield richer and brighter colors. Not
true as you can see by the example in Visual 2. aRGB uses the same color space
as sRGB and expands therefore more colors on the outer edge are available. This
will make the greens and blues in your prints look richer (trees and water).
It does expand slightly into reds and yellow but you can match this in Photoshop
with saturation, etc. For commercial applications as an example aRGB will be
able to reproduce blues for banners more accurately. sRGB would have to take
its best guess.
With aRGB the crayons spread out and Photoshop filled the spaces. Some experts
say that skin tones do not look as smooth as in sRGB images. Will the average
untrained eye or yourself spot that - not likely. The experts even agree on
this. aRGB will print with more colors. Better tones vs. more color? It’s
your choice.
Too bad most web browsers and hosting sites cannot display aRGB color space.
Not yet anyway. aRGB was not meant for web viewing but we can make changes so
it can. Excerpt from smugmug: “No windows based browser can display it
correctly. The Macintosh Safari and Internet Explorer can, but only under conditions
not normally found in every day browsing”. Remember the majority of the
world is geared for sRGB. This is why your cameras default is set to sRGB. As
stated earlier aRGB was developed to obtain more color from the printer.
The Macintosh browsers Safari and Internet Explorer can, but only in everyday
browsing. The Macintosh browsers Safari and Internet Explorer can, but only
under
If you choose to take full advantage with aRGB there will be some work involved
on your part. You have to make sure your camera can capture in aRGB color space,
your monitor can see it and your printer can print it. If they all can you will
have to calibrate/profile your monitor and printer. If your equipment can’t,
you will have to purchase it and that can be expensive.
If you shoot in JPEG and set your camera to sRGB your camera's sensor will
capture color in the sRGB color space. Set it to aRGB and it will capture in
aRGB color space. RAW is so great. If you shoot in RAW it will ignore the -
sRGB or aRGB color space settings. Raw is just data and the camera’s sensor
dictates the available color space it can capture. All cameras are different
but most DSLR sensors will capture aRGB color space and even beyond. Check yours
to see what it can do. Look at Visual 2 again and imagine that your crayons
are now spreading well beyond the aRGB borders. Now you are getting into ProPhoto
RGB. Unless you’re familiar with this and have high end equipment, now
is the time to forget about ProPhoto RGB.
1. Shoot in JPEG and set your color space to sRGB. No problems here.
2. Shoot in JPEG and set your color space to aRGB. We can convert aRGB color
space to sRGB for the web viewing later.
3. Shoot in RAW. You have all the benefits of RAW and you have a choice of
what color space to work with. Remember RAW is just data. You can change the
color space to sRGB or vise versa. See visual 3. Adobe Camera Raw (ACR) is opened
in Photoshop. If you are using a different RAW converter check the color space
settings! Look at the lower left corner. Here is where you change the color
space. When you change color space you will see ProPhoto RGB and others here
so just ignore those.
VERY IMPORTANT!
If you choose to work in aRGB ensure that you set your camera to aRGB. Even
though your camera is set to RAW and does not know the difference between aRGB
and sRGB your camera does attach the information of which color space you took
the picture in. This is so you can keep track of what you are doing. To put
it simply if you shoot in aRGB color space and decide to convert to sRGB, Photoshop
gets confused. This is the standard workflow and will make file management easier.
Before you do this you must read the section on How To Convert aRGB to sRGB
for Web Viewing and Printing to better understand this. If you decide to shoot
in and work in sRGB set you camera to sRGB and then make sure you set the color
space to sRGB on Visual 3.
Visual 3
Adobe Camera Raw
Everything that I have said now points to working in sRGB. Now, I am getting
into a controversial area, a subject with much debate. Can your monitor see
all the colors in the aRGB gamut? Can all the monitors around the world see
your image they way you see it? Who knows, however technology is improving,
equipment is becoming more consistent and many monitors and sRGB printers can
see and reproduce color beyond the sRGB borders. This is a suggestion by Andrew
Rodney. The best thing to do is to work in aRGB since it gives you the additional
data that may be captured that you might be able to see on you monitor and reproduce
from your printer. His suggestion is to shoot in RAW and aRGB, set the format
to TIFF, and when complete, convert to sRGB web viewing and printing. See what
your system can do. Even try ProPhoto RGB if you want to. Andrew Rodney answered
many of my questions at dpriew.com. Later I looked to see who he was. Check
out his profile. I was surprised he gave me his time. (http://www.digitaldog.net)
Andrew states this is a good process to use, however others state there is
a danger here since you don’t really know how much color outside of sRGB
color space Walmart can handle. It’s one thing doing this for a hobby
and it’s another messing up an important event. I do not want to cause
you a problem so some tests.
Do not try these tests until you read -"How To Convert aRGB to
sRGB for Web Viewing and Printing"
RAW Shooters: Set you camera to RAW and aRGB then take picture
with a lot of color. Open in ACR or your preferred RAW converter. Make sure
the color space is on aRGB, set the format to TIFF and process the image. Work
on your image and record what you did, convert to sRGB then save the image.
Open the same image in ACR or your preferred RAW converter again, this time
change the color space to sRGB set the format to TIFF and process you image.
Work on your image using the same steps you recorded.
JPEG Shooters: Find a scene with a lot of color and set your
Camera on a tripod. Take two pictures one in aRGB and one in sRGB. Work on your
image and record what you did then do the same to the other.
Compare them on the screen, print them at home and send the files to Walmart.
Did it make a difference? Do you like what you see? Is aRGB better or worse
for you?
If you are shooting in RAW and aRGB and you have an important event like a
wedding you have nothing to lose shooting RAW. If a test print does not look
good go back and change the color space to sRGB. If you want that comfort level,
just shoot in sRGB for that wedding. If you shoot in Jpeg you may want to seriously
consider using sRGB just in case, unless you are confident this works for you.
Again Andrew Rodney suggested the method and many people use it. All over the
forums it is repeated “don’t forget to convert to sRGB”. The
reason some think this is dangerous and Walmart wants you to send a file in
sRGB is because they don’t want to deal with aRGB, but they don’t
know about the next section. Also if you choose to work in aRGB you may want
to think about profiling your monitor.
If you decide to just work in sRGB the next section on how to convert may not
be useful to you. You should at least read the section - Should I use
“Save For Web” or “Save As” so you know how
your image is handled on the web.
Before we Proceed you Must set your Color Settings and Color Management
Policies in Photoshop First
This will become very important later. On the top bar select “Edit”
then “Manage Color” Set you all your settings to match the ones
in Visual 4
The key ones are:
Working spaces - Adobe RGB ((1998) – this is the color
space you will be working in.
Color Management Policies - Set them all to Preserve Embedded
Files – this will be important after you convert aRGB to sRGB.
Check the - Profile Mismatches, Missing Profiles and Ask When Pasting
boxes. These will be important for opening documents later.
Visual 4
NOTE: If you don’t plan to convert later change the Working
Space to sRGB, set Color Management Policies to OFF and uncheck the Profile
Mismatch, Missing Profile and Ask When Pasting boxes. Since you’re using
one color profile there will be no need for these.
A Test First
Open an aRGB image in Photoshop. Make a duplicate and close the original (you
should always do this in case you want to start from the beginning). On the
top bar select ”Edit” - “Assign Profile” menu. Make
sure sRGB IEC61966.2-1 is in the Profile Dialogue box. See visual 5. If not
select it. I will refer to it as sRGB from this point on.
Visual 5
Now toggle between it and “Working RGB” and watch the image change
before your eyes. The dull image represents what would happen to it if you worked
on it in aRGB and did not convert from aRGB to sRGB then sent it to Digital
Image Café or printed it. Make sure to put it back to Working RGB when
you’re done and do not use this again until you learn more about color
management. The next step solves the problem.
Make a few changes to your image then resize for web viewing. Your workflow
may be “Save as” or “Save for Web”. Either way before
you save, select “Edit” - “Convert to Profile” and in
the “Destination Space” select sRGB then click OK. See Visual 6.
You have just converted the aRGB color space to sRGB color space and you will
notice the color did not change. When you use the “Convert to Profile”
this is what happens. I will try to keep this explanation to a language I can
understand so here is my version of this. Photoshop explains to sRGB “I
realize I’m sending you aRGB color space values but try to keep them as
close to the aRGB color space values as you can”. Imagine you’re
tricking it. Since you did all your work in aRGB, this is the color you want
to retain when sending it down the pipe.
Visual 6
Digital cameras capture all the information about the shot you took. ISO, shutter
speed, exposure and so on. It will even list your custom function settings.
This is called EXIF data. This is very handy if you want to trouble shoot an
image. It can be sent to friend or posted in a forum and the shot can be analyzed.
Use “Save As” if you want to keep it attached.
“Save for Web” strips EXIF data from the image. Stripping EXIF
data makes more room in the file, which should allow you to bump up the image
quality. At DIC we are limited to 300K and we may as well get as much image
quality in as we can.
Open Save for Web. See Visual 7. There is an arrow button to the upper left
area of the Save command. Click on it and ensure Uncompensated Color
is selected.
“Save For Web” will automatically optimize your image quality.
Make sure that you have selected Jpeg and check the Optimize Box.
NOTE: Some earlier versions of Photoshop do not have "Save
For Web".
Visual 7
Just above the Optimized checkbox is another arrow button. Click it and the
select “Optimize to File Size”.
I enter 290K. See visual 8. I have tested from 300K and down and I do not get
any file size warnings from DIC with this value. Feel fee to test it out. You
always have to follow these steps for each file you save even if 290 is entered.
Also it leaves your original file as is after you saved for web. If you try
and close without saving it you get a warning so it’s harder to make a
mistake.
Visual 8
What about the ICC profile checkbox when using Save For Web?
When you check this you are embedding the color profile information to your
file. See Visual 9. This is also known as tagging. You save a file with a profile
(tag) for a distinct reason. That reason being, that you want the person opening
the file to know what profile you were working in at your end. Here is where
you can include printers. Now, the only way that the other person(s) will know
how your profile tagged file will look is if they're viewing it with a Color
Managed Application like Photoshop or a printer. Most web browsers
and Windows itself are color stupid and the embedded profiles have no meaning
to them. When non Color Managed Application devices receive
a file that does not have color profile information they automatically assume
it is sRGB. So if you CONVERT your data to sRGB and save it without embedding
a profile, the color stupid viewing devices will be able to get a decent idea
of what you do, provided yours and their monitor(s) aren't really off (good
reason to calibrate yours).
Visual 9
Therefore web browsers don’t require color profile information to view
images at websites like DIC, etc. If you want to continue using “Save
As” there is nothing wrong with that. The sRGB checkbox is checked by
default when using Save As. You can uncheck it if you wish. If things are going
well for you just keep on doing what you have been doing. For Save As users
if you want to check it ICC box go ahead.
Clearing Up Some of the Confusion
You used “Save for Web” and you did not check the ICC profile box.
If you open in Photoshop and you have not told Photoshop to warn you of this
(color management policies in visual 4), it will not know the color profile,
ignore the work you did and revert to the aRGB default colors. aRGB default
colors will look oversaturated. This is why I believe some people think using
“Save for Web” changes the color. This definitely threw me off.
I tested using Save for Web and Save As and sent them to an image hosting site
and compared both. There was no change to the color. This was also can be proven
by color measurement readings. If you send your file using “Save for Web”
to someone who will view in Photoshop, either tag it by clicking the ICC Profile
box or inform them so they can view it in the correct color profile. This also
applies to Save As, however the ICC box is checked by default.
Let’s Take a Run at Using Save for Web
I will not discuss Save As here. Once you understand using how Save for Web
works you can apply it for Save As.
Create two folders. Name one Pre Web Final. This is where
you will store the final work of art. Name the other Web Final.
This is the where you will store your files that will be sent to sites like
DIC. This is my workflow. You can change everything later to suit yours.
1. Open an aRGB file
2. Make duplicate in case you want to start from the beginning. Always a good
thing to do.
3. Close Original
4. Work on the file and resize it for the web.
5. When complete use Convert to sRGB and Click OK
6. Use “Save for Web” (do not check the ICC profile box), rename
the file and save in the Web Final folder
7. For your working file (still left on your screen) use “Save As”,
rename and store in the Pre Web Final folder. If it’s
a TIFF file, leave it as a TIFF file. Just click OK at the TIFF
Options.
Opening a Saved File
If you are not happy the image you can open the file in the Pre Web
Final Folder or the Web Final folder. It’s your
choice, but I would work on the Web Final file. If you really
mess it up you can delete it and go to the Pre Web Folder file.
Earlier we did two things 1. Instructed Photoshop to Preserve Embedded Profiles
and warn you about Embedded Profile Mismatches and Missing Profiles (Visual
4). You also converted your sRGB profile to aRGB profile (Visual 6). Now you
will get warnings when you open your files. Don’t worry - these warnings
are a good thing.
VERY IMPORTANT:
Since you converted your color profile to sRGB you want to open it in sRGB.
Opening the Pre Web File
You converted the profile from aRGB to sRGB. You instructed Photoshop to warn
you about this (visual 4) therefore you will get a Color Profile Mismatch warning.
See Visual 10. You also instructed Photoshop to Preserve Embedded Profiles so
the “Use the embedded profile (instead of the working space)" button
should be automatically illuminated. If not select it. Click OK and you’re
off to the races.
NOTE: you will get this also get this warning if you change your
color profile in Visual 4 and try to open that file.
Visual 10
If you wish to make changes there are two options 1. The best one is to just
go ahead and just make them. You have probably done the majority of work earlier
so if you are doing a minor touch up like cloning out a spec, etc there is no
pressing reason to convert to aRGB. If you want to anyway you can (visual 11).
When done you remember convert back to sRGB.
When done just use “Save As” and overwrite or save as a new file.
Visual 11
Opening the Web File
When you used Saved For Web you did not check the ICC Profile box. Now Photoshop
does not know what the color profile is. You instructed Photoshop to warn you
about this in the Color Management Settings (visual 4) therefore you will get
a Missing Profile warning (Visual 12) Select sRGB in the Assign Profile dialogue
box.
Visual 12
Again you have 2 options. Just like the Pre Web file you can work in sRGB
or aRGB. Again the best option is to work in sRGB. If you want to work in aRGB
check the “then convert the document to working RGB” checkbox. (You
can convert manually later this just saves you a step). If you don’t,
do not check this box. If you decide to work in aRGB remember to covert back
to sRGB when done.
When done just use “Save for Web” and overwrite or save as a new
file
NOTE: If you want compare the changes you are making, open the
Pre Web file to view and work on the Web File only.
Open the original aRGB file (we have been working on the duplicate) and you
will have no warnings. This is because we did not convert profiles so Photoshop
knew how to open the file. Your printer needs color profile information to print.
Click in Save As and you can see the ICC profile is aRGB. See visual 13. Press
Cancel.
Visual 13
Make a duplicate of the image and Convert to sRGB. Use Save As. Now you can
see that the Color Profile is sRGB (Visual 14). When you open this document
later you will have to answer the Profile Mismatch warning. See visual 10
Visual 14
Conclusion
You should now have a better idea of color space. If you want to use the full
potential of Adobe RGB you will have to make sure your equipment can do the
job. If you want to be safe and still work with great color stick with sRGB.
If you’re adventurous and want to push the envelope work with aRGB and
convert to sRGB.
RAW saves the day. As technology improves we may be able to achieve full potential
in the aRGB color space at reasonable cost. You may want to experiment with
your new sRGB printer. Even if your camera is set to sRGB you know it captured
aRGB color space. That will be there forever.
Remember, it makes no difference if you send an aRGB or sRGB file (tagged or
untagged) the Web Hosting site will ignore all information and view it in sRGB
color space. Do not forget to convert your aRGB masterpiece to sRGB. If you
don’t the color will change when you open it at DIC just like in the example
in Visual 5.
When you become comfortable with all of this you may want to learn about the
other Color Management Policy warnings, etc in Visual 4. These may be of use
to your workflow some day. For now just enjoy your new set up.
Hope this clears some up of the mystery about color space. I hope you enjoyed
reading it as much as I did working on it.
I would like to thank Digital Image Café member Michael Robichaud for advising me about an important piece to the puzzle.
Michael added - You should set your monitor to match the color space you are working in. In Windows, right click on desktop to go Display Properties->Settings Tab->Click on Advanced button and then the Color Management Tab add profiles for sRGB, Adobe RGB 1998, and or ProPhoto RGB. Your monitor may need to be "calibrated" but it may help when working in the desired color space.
It would not be a bad idea to purchase a monitor calibration device such as a Spyder or a Pantone Huey as these devices will calibrate and profile your monitor. There are many makes and models so you will have to do some research. Then if you decide to you could also profile your printer if color matching is important to you.
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