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Author Topic: Printing color space, why we don't print in sRGB  (Read 6633 times)
tived
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« on: March 09, 2009, 10:19:50 PM »
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Hi guys,

I was a bit stunned, when a fellow photographer told me, that he prints his work in sRGB on a Epson 9xxx latest model, and recommended that i do the same on the HP Z3100. The boss asked me, well why don't we print in sRGB.

Ok, why not? I am a bit lost for words, because it goes against the grain of what i have learn over the years about printing and color management. Maybe someone here can help me make my point  a bit more fluently then I am able to.

So I was wondering if anyone can direct me in right direction, link me to some web site which clarifies why it is not a good option to print in sRGB, when printing portraits and fine art prints.

What I came up with initially was that it was a much smaller color space and therefore it would clip the more saturated colors and anything that is outside the sRGB colorspace compared to the AdobeRGB color space that we edit work in.

I guess, one workflow where one could use sRGB, would be if you always nailed your exposures, shot JPEG and always printed to the same printer (small gamut printer)

I might be wrong, but i thought that both the Epson and HP's latest line of printers have larger gamuts then sRGB, but smaller then AdobeRGB

can someone please help me set this straight, thanks

Henrik

PS: Better yet, if I can demonstrate why, such as printing an image that indicates that this is why we don't print in sRGB.

I am pretty sure I was told this in a workshop, but just can't find the notes and have never bothered with it as I wasn't printing in sRGB
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Avalan
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« Reply #1 on: March 09, 2009, 10:58:01 PM »
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Hi Henrik

You may find your answer in the following links:

http://www.luminous-landscape.com/tutorial...photo-rgb.shtml

http://www.adobe.com/digitalimag/pdfs/phscs2ip_colspace.pdf

Avalan
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tived
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« Reply #2 on: March 10, 2009, 12:00:47 AM »
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Thanks Avalan

i am having a look at it - just need to proof my point :-) thanks

Henrik
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Avalan
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« Reply #3 on: March 10, 2009, 12:48:09 AM »
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You are very welcome.

The other thing to add as an observation:

The working color space in all of the CONSUMER printing market I have seen(including most of the pay to print or one-hour labs), is srgb.probably because they are dealing with a large number of amature phtographers with no clue about color management, and dealing with jpg files, etc.

Most professional print making companies I have seen, are using adobe RGB for their color space.

The high end Printing companies  probably will use pro photo RGB. They have fully color managed workflow, and capable of getting advantage of the high gamut of the new inkjet printers which EXCEEDS the adobe RGB.

Avalan

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bjanes
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« Reply #4 on: March 10, 2009, 07:13:24 AM »
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Quote from: tived
Hi guys,

I was a bit stunned, when a fellow photographer told me, that he prints his work in sRGB on a Epson 9xxx latest model, and recommended that i do the same on the HP Z3100. The boss asked me, well why don't we print in sRGB.

Ok, why not? I am a bit lost for words, because it goes against the grain of what i have learn over the years about printing and color management. Maybe someone here can help me make my point  a bit more fluently then I am able to.

So I was wondering if anyone can direct me in right direction, link me to some web site which clarifies why it is not a good option to print in sRGB, when printing portraits and fine art prints.

What I came up with initially was that it was a much smaller color space and therefore it would clip the more saturated colors and anything that is outside the sRGB colorspace compared to the AdobeRGB color space that we edit work in.

I guess, one workflow where one could use sRGB, would be if you always nailed your exposures, shot JPEG and always printed to the same printer (small gamut printer)

I might be wrong, but i thought that both the Epson and HP's latest line of printers have larger gamuts then sRGB, but smaller then AdobeRGB

can someone please help me set this straight, thanks

Henrik

PS: Better yet, if I can demonstrate why, such as printing an image that indicates that this is why we don't print in sRGB.

I am pretty sure I was told this in a workshop, but just can't find the notes and have never bothered with it as I wasn't printing in sRGB

For a brief answer, printers are highly non-linear devices and no printer has sRBG as its native working space. If you send an image in sRGB directly to a printer, you will get gastly results. You can test this yourself with an image in sRGB. In the print dialog have Photoshop manage the color and turn off color management in the printer. Then send the image to the printer using sRGB as the working printer profile and see what you get. This happens to me occasionally when I am working quickly and forget to set up color management properly.

Most big box photo printers such as CVS, Walgreen's, Sam's etc expect the files to be in sRGB, which is what most amateur photographers use with their P&S cameras. The printer then converts the image using a profile made for the printer. Costco is one of the few mass outlets that can provide you with a color profile for the printer. It expects sRGB unless you specifically indicate otherwise. Most pro labs will supply you a profile.

Bill
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Mark D Segal
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« Reply #5 on: March 10, 2009, 08:31:55 AM »
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I think the simplest way of putting this to the person who asked that question of the O/P is the fact that recent higher-end inkjet printers have colour gamuts whose boundaries exceed sRGB and, with different shapes than those of the working space, exceed ARGB(98) in some areas. So confining the images to an sRGB gamut will often clip highlights and shadows, causing noticeable loss of highlight detail and muddying of shadow tones. You may also notice a scattering of duller colors depending on the image. Go to Bill Atkinson's website, download page, and download his printer test target image. Make a copy. Shrink one copy to sRGB and leave the other one untouched. Print both and compare. That will speak for itself.
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Mark D Segal (formerly MarkDS)
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Wayne Fox
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« Reply #6 on: March 10, 2009, 03:53:38 PM »
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Quote from: tived
Hi guys,

I was a bit stunned, when a fellow photographer told me, that he prints his work in sRGB on a Epson 9xxx latest model, and recommended that i do the same on the HP Z3100. The boss asked me, well why don't we print in sRGB.

I doubt he is actually printing in sRGB.  He may be sending his files to the printer in sRGB, but most likely he is using Printer manages color in Photoshop.  This means the printer driver is actually doing a conversion to the output device.  It is possible he is using ColorSync to apply the output profile which then would result in very similar results, but most likely he is just using the built in Epson Color controls. Either way, sRGB is not going directly to the paper.  If he is using the epson color controls, this is a common mistake by those that struggle to get good color using output profiles. Since the printers color controls are expecting an sRGB file, they will usually do a sort of OK job in printing the image.  I would tell your boss this person doesn't understand color management at all, and instead is using a hack to achieve "ok" results.  In fact, he is using his high end printer as though it were a $100 consumer printer from Best Buy.

All output devices require some type of data conversion for your file from its working space, which in this case is sRGB. You can convert via a device specific output profile(best) or some type of intermediate conversion step (such as Epson Color Controls or silver halide printers internal LUT conversions.) But sRGB isn't going to the paper.

This is actually quite similar to the consumer silver halide printers used in places like Walgreens (Noritsu or Fuji Frontiers).  They are engineered from the ground up to expect an sRGB file coming in, and proprietary software or firmware will then modify the colors using the printers internal LUT's to provide acceptable results. These are fairly low gamut devices (smaller than sRGB), and in addition require constant monitoring and calibrating because the RA-4 process drifts dramatically.  It's a mistake to think that sRGB is their output profile.  It's just the space the system has been engineered to accept to make their own internal conversion.

I guess the question I would ask is why would you want to do this?  What advantage is there?  It isn't any faster.  While the work may be acceptable, it will be lower in quality  than using appropriate color management tools, and sometimes will be so bad it will require you to adjust the file.  If the file is a .jpg things can get ugly real fast.  There is no disadvantage to doing things the right way.

It is much better to use good color management practices.  A good profile will characterize your printer/paper combination allowing you to achieve the maximum quality it can deliver, which as mentioned by others include gamuts containing some colors which exceed sRGB  and AdobeRGB.  (As long as you don't clip the colors by using sRGB as your working space in Photoshop).  The accuracy of the conversion to the printer space is magnitudes better than simple color controls in the printer driver.  You also have a much better chance in achieving a decent monitor to paper match.
« Last Edit: March 10, 2009, 04:14:51 PM by Wayne Fox » Logged

pegelli
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« Reply #7 on: March 11, 2009, 01:39:36 AM »
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Isn't there also be a bit "horses for courses" aspect for this?

Assuming you're printing in 8 bit you have 256 levels to spread your color gamut over.

So if you've got a muted low saturation image that fits within the sRGB space you're actually spreading the gradients over more levels. Doing that in adobeRGB or prophotoRGB would just discard more levels on the extremes and spread the tones in the image over less levels.

So :
- low saturation images where the tones fit within the sRGB space is fine and makes optimum use of the available levels
- high saturation images with tones outside the sRGB space need adobeRGB or even prophotoRGB to show their richness.
« Last Edit: March 11, 2009, 01:42:06 AM by pegelli » Logged

pieter, aka pegelli
bjanes
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« Reply #8 on: March 11, 2009, 08:29:38 AM »
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Quote from: MarkDS
I think the simplest way of putting this to the person who asked that question of the O/P is the fact that recent higher-end inkjet printers have colour gamuts whose boundaries exceed sRGB and, with different shapes than those of the working space, exceed ARGB(98) in some areas. So confining the images to an sRGB gamut will often clip highlights and shadows, causing noticeable loss of highlight detail and muddying of shadow tones. You may also notice a scattering of duller colors depending on the image. Go to Bill Atkinson's website, download page, and download his printer test target image. Make a copy. Shrink one copy to sRGB and leave the other one untouched. Print both and compare. That will speak for itself.

Mark,

I think your analysis needs a bit of clarification. AFAIK, the dynamic ranges of sRGB and ProPhotoRGB are the same in that they both encompass the same range of luminances--from black to white. Where they differ is in the range of color saturation that they can encode--ProPhoto has a much bigger color gamut. If the highlights and shadows in an image have no color then there will be no difference in their dynamic range. When one looks at the two spaces in terms of the L*a*b system, they both can go from L* of 1 to 100, but sRGB is much more restricted in the range of a and b. This is shown in a 3D gamut plot of the two spaces. A characteristic of RGB spaces is that they both are constricted at high and low luminances as is shown in the plot. If your images have color in the highlights and shadows, you will have more saturation clipping in the smaller space.

[attachment=12062:sRGB_ProPhoto.png]

To test this hypothesis, I made dynamic range plots of a Stouffer wedge showing the entire DR of my camera using 16 bit sRGB and ProPhotoRGB using ACR with a linear tone curve except for the gamma encoding. The DR is the same.

[attachment=12063:stouf005...hotoComp.png]


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Mark D Segal
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« Reply #9 on: March 11, 2009, 08:36:49 AM »
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Quote from: bjanes
Mark,

I think your analysis needs a bit of clarification. AFAIK, the dynamic ranges of sRGB and ProPhotoRGB are the same in that they both encompass the same range of luminances--from black to white. Where they differ is in the range of color saturation that they can encode--ProPhoto has a much bigger color gamut. If the highlights and shadows in an image have no color then there will be no difference in their dynamic range. When one looks at the two spaces in terms of the L*a*b system, they both can go from L* of 1 to 100, but sRGB is much more restricted in the range of a and b. This is shown in a 3D gamut plot of the two spaces. A characteristic of RGB spaces is that they both are constricted at high and low luminances as is shown in the plot. If your images have color in the highlights and shadows, you will have more saturation clipping in the smaller space.

[attachment=12062:sRGB_ProPhoto.png]

To test this hypothesis, I made dynamic range plots of a Stouffer wedge showing the entire DR of my camera using 16 bit sRGB and ProPhotoRGB using ACR with a linear tone curve except for the gamma encoding. The DR is the same.

[attachment=12063:stouf005...hotoComp.png]
Bill, yes, I agree. I wasn't referring to DR, I intended that comment to apply to colour gamut and the impact on rendition of detail where pre-existing colours anywhere accross the whole spectrum of DR may have been clipped by shrinking the colour space.
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Mark D Segal (formerly MarkDS)
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Ernst Dinkla
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« Reply #10 on: March 11, 2009, 08:51:42 AM »
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Quote from: tived
Hi guys,

I was a bit stunned, when a fellow photographer told me, that he prints his work in sRGB on a Epson 9xxx latest model, and recommended that i do the same on the HP Z3100. The boss asked me, well why don't we print in sRGB.


Sometimes it is better to satisfy the customer, your boss and have less headaches yourself.  The Z3100 driver also has CM of its own and a choice between AdobeRGB and sRGB. Set it at sRGB, use no CM in the application. With HP's papers it will work to a degree. Do the job or a proof that way for that customer and tell him that it is done specially for him. Tell your boss that it isn't the best method in all cases but suitable for that customer. In the end the customer will complain that the heavy reds are not the same to the ones he prints on his latest Epson wide format model. Whatever CM method or space you will use it will be difficult to reproduce that red on the Z3100. Wonder why he goes to your shop in the first place with a wide format printer at home.



met vriendelijke groeten, Ernst Dinkla


New:
http://www.pigment-print.com/dinklacanvaswraps/index.html

Try: http://groups.yahoo.com/group/Wide_Inkjet_Printers/
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tived
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« Reply #11 on: March 21, 2009, 11:17:38 PM »
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Thanks everyone for your replies.

Conclusion is that we will not be printing and delivering the printer sRGB files :-) and keep working in high bit color and as a minimum use AdobeRGB for color space. I have never gotten a response from the friend of the boss as to why he is wanting to send sRGB files to his Epson 9900. So this one here is left hanging in the air

thanks, it has been very good to read all the feedback

Henrik
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