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Discussion Board -> Photography -> sRGB vs Adobe RGB

sRGB vs Adobe RGB

tbhockey
07/21/05 10:35 PM GMT
I am happy to say that i recently purchased a Canon 350D =)

Now, I was wonder what the difference is between sRGB and Adobe RGB, the booklet doesnt go into much detail...
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-tbhockey

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::philcUK
07/21/05 11:16 PM GMT
sRGB is a RGB colour space proposed by HP and Microsoft because it approximates the colour gamut of the most common computer display devices. Since sRGB serves as a "best guess" for how another person's monitor produces colour, it has become the standard colour space for displaying images on the internet. sRGB's colour gamut encompasses just 35% of the visible colours specified by CIE (see section on colour spaces). Although sRGB results in one of the narrowest gamuts of any working space, sRGB's gamut is still considered broad enough for most colour applications.

Adobe RGB 1998 was designed (by Adobe Systems, Inc.) to encompass most of the colours achievable on CMYK printers, but by using only RGB primary colours on a device such as your computer display. The Adobe RGB 1998 working space encompasses roughly 50% of the visible colours specified by CIE-- improving upon sRGB's gamut primarily in cyan-greens.
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"Some mornings, it's just not worth chewing through the leather straps"
trisbert
07/21/05 11:18 PM GMT
SRGB allows a reasonable print without any processing. ARGB contains a wider range of colours and allows you to get a brighter more accurate print after processing in an image editor, they tend to look flatter on screen though.
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There are three colours, Ten digits and seven notes, its what we do with them that’s important. Ruth Ross
::philcUK
07/21/05 11:24 PM GMT
unless, of course, you calibrate your screen with an Adobe RGB profile that is.

basically - to get the best detail from your 350 - shoot in RAW format with an Adobe RGB gamut....
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"Some mornings, it's just not worth chewing through the leather straps"
tbhockey
07/21/05 11:37 PM GMT
ok. thanks for all the help. Now say i there was i picture i wanted to upload here. Would it look bad if it was Adobe RGB?
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-tbhockey
brphoto
07/22/05 12:10 AM GMT
Shoot in Adobe 1998, do your Photoshop post processing and then go Convert to Profile, sRGB IEC61966-2.1 at the very end. Make sure the conversion intent is "Perceptual". This will produce the brightest, most pleasant colors.

Here’s a tutorial on how to do this.

The reason for converting is that programs like Internet Explorer are not profile aware, so they don't recognize the Adobe 1998 tag. Converting, perceptually, to sRGB maintains the vivid Adobe 1998 colors and allows non profile-aware programs to display them.
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"If I could tell the story in words, I wouldn't need to lug around a camera."
tbhockey
07/22/05 2:29 AM GMT
wow thanks alot Will. sounds complex, but i think i can get that down...we'll see =)
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-tbhockey
MiLo_Anderson
07/22/05 5:37 AM GMT
Does anyone have any suggestions on properly calibrating a moniter to the adobe gamut? I'm not really sure about all the options it gives you.
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"A piece of toast with butter always lands butter side down, and a cat always lands on its feet. What happens if a piece of toast is tied butter side down to the back of falling cat? Does it hover above the ground in perpetual indecision?"
brphoto
07/22/05 5:58 AM GMT
Do you mean using Adobe Gamma?

It's a highly inaccurate method of calibration since you are "eyeballing" it using squares on the screen. When it comes to monitor calibration, you are creating a profile of how the monitor displays colors and then the computer adjusts the output to according to the profile. If you use a monitor calibration tool and software, you set your monitor to a desired target (I have mine set to D50 or 5000K and Gamma 2.2) based on your needs, eg. web or printing.
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"If I could tell the story in words, I wouldn't need to lug around a camera."
MiLo_Anderson
07/22/05 6:10 AM GMT
Alright, see that right there proves i need help:P. I was trying to use adobe gamma. I haven't completely followed what you said, but i think i caught most of it. But that leads me to a couple new questions. Where do i go to set these settings? Just in the adobe gamma thing in the control pannel, or is there somewhere better. My second question what kind of settings would you suggest. I probably mostly view my pictures on my screen, and put them on the internet, but i sometimes do take them in for finishing, and occasionly get some done 8x10 or so to frame for a wall or what ever. And also thanks again for your awesome help in the technical side of stuff like this.
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"A piece of toast with butter always lands butter side down, and a cat always lands on its feet. What happens if a piece of toast is tied butter side down to the back of falling cat? Does it hover above the ground in perpetual indecision?"
brphoto
07/22/05 6:47 AM GMT
You can set the target gamma using the box with the numbers in the Adobe Gamma dialog.

After it walks you through the monitor phosphors, etc, you come to a screen/page where it has a larger grey square with a smaller light grey square inside it. Below this is where you set the target gamma, the slider is used to actually achieve the desired gamma. Adobe gamma is found in the Control Panel. (I use the Gretag Macbeth Eye-One to calibrate my monitors, it has special software that, in combination with a device that suction-cups on the screen, profiles and calibrates the monitor.

If you are mostly posting to web, then use Gamma 2.2 and a white point of 6500K (this is the Windows de facto standard). I use a white point of 5000K (a little too warm looking for some) because the lab I send my files to (Technicare in Calgary) specifies that the monitor's white point be 5000K to assure that the prints match what's on screen.

If you want a monitor that you can absolutely trust for color/tone accuracy, then I would recommend investing in a monitor calibration tool (they range from about 200$ to several thousand depending on how complex you want to get). Otherwise, eyeballing it works alright if it's not a color-critical situation.

I'll let Phil chime in on this in case I missed something, as he's the expert on color management.
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"If I could tell the story in words, I wouldn't need to lug around a camera."
::philcUK
07/22/05 7:49 AM GMT
Expert? *awkward blush* erm... The Gretag kit is great and their name has become the defacto standard in colour managment...but at a price... if your not feeling flush purchase a Pantone Spyder2 from Colorvision. they are about as cheap as it gets for calibrating devices but are very effective. I also use 5-5.5K as a white point because that is what the daylight lamps in my viewing booths operate at so I try to keep it as consistent as possible.
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"Some mornings, it's just not worth chewing through the leather straps"
MiLo_Anderson
07/22/05 8:14 PM GMT
Thanks for the help again. As far as getting equimpment to perfectly calibrate, i think that could be alittle extreeme for me being a hobiest. it is quiet intresting though, and i can see how it could be nessary. I have got prints back that did looke a fair amount differnet then i expected them to be.
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"A piece of toast with butter always lands butter side down, and a cat always lands on its feet. What happens if a piece of toast is tied butter side down to the back of falling cat? Does it hover above the ground in perpetual indecision?"
trisbert
07/22/05 11:53 PM GMT
Removed this one because the topic seamed to flow around it.
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There are three colours, Ten digits and seven notes, its what we do with them that’s important. Ruth Ross
d_spin_9
07/24/05 9:39 PM GMT
dont upload anything to the internet unless it is sRGB because it will do a VERY poor conversion from your files aRGB to sRGB which is the only thing browsers can display
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The heavens declare the glory of God, the skies proclaim the work of His hands.
+mayne
07/25/05 3:22 AM GMT
Now you tell me...
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Darryl

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