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Author Topic: Printing/colour management  (Read 281 times)

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Offline Annie

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Printing/colour management
« on: 10:12:01, 19 March, 2017 »
In the abscence of many/any clear nights recently I've been concentrating on processing and have just started Scott Ireland's Photoshop Astronomy.  He begins by looking at 'the digital darkroom' and colour management and when setting up photoshop for colour management suggests selecting Adobe RGB (1998) in Photoshop. My printer however  - Canon Pro 100S - has a default setting of sRGB and doesn't offer the option of Adobe RGB (1998).  If I set Photoshop to handle colour management does anyone know whether this difference will have any impact when I print?

Annie

Offline chris.bailey

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Re: Printing/colour management
« Reply #1 on: 10:28:49, 19 March, 2017 »
Annie

The whole colour management thing is a bit of a mare. Ideally you would have a profile for your screen and another for the printer (being really pedantic you would have profiles for each printer/paper type combination). This way what you see on the screen will give a reasonably true interpretation of what comes out of the printer.

Adobe RGB is quite a wide gamut profile and bigger than most screens will present and certainly a lot more than any but very high end CMYK printers will give you. sRGB is a much small colour space (gamut) and more likely to be covered by the screen/printer but may not translate correctly to print. Photoshop enables you to proof the profile i.e. you change the screen representation to match that of the destination. It only works well however on high end calibrated screens.

A good test it to load a test RGB image such as http://www.colour-science.com/quality%20test%20tools/test%20files/test%20files%20overview.htm and print it out and compare how it prints out to the screen representation. Most printers have their own colour management, to produce highly saturated pretty holiday snaps. You ideally want to turn off printer colour management and let Photoshop do the colour management. Canon and Epson printer drivers install profiles for their printers and papers so you choose say "Epson - Premium Glossy" as the print profile within Photoshop. "Epson - Premium Glossy" is actually a colour profile. I tend to use Olmec printer paper and they produce profiles for each of their papers which I find work well.

I suspect the reason Adobe RGB format is suggested as a base point is that it is more accurate to go from a large colour space (gamut) to a smaller one than the other way around so you start with Adobe RGB and then reduce it for the screen and then the printer. There are settings somewhere in Photoshop as to how such colour space changes are handled.

Chris

ps https://en.wikipedia.org/wiki/Color_space gives a reasonably concise explanation of colour spaces.
As I say it is more than a little complex and really beyond most domestic printers
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Offline Annie

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Re: Printing/colour management
« Reply #2 on: 11:03:29, 19 March, 2017 »
Thanks for the links Chris.  Yes it is complex.  Scott Ireland does a pretty decent job of bridging the gap between making it too basic and ridiculously complex.  I think I will follow his directions in setting up photoshop to handle colour management  and then use the colour science link for a test shot as you suggest.  I will be relieved to move on to the next chapter - 'The Histogram and Levels - Defining Tonal Range'!

Thanks again.
Annie

Offline Annie

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Re: Printing/colour management
« Reply #3 on: 11:36:08, 19 March, 2017 »
Have just got to Scott Ireland's explanation as to why he suggests using a wider gamut working space than sRGB "today's photo inkjet printers can produce colours that lie outside of the sRGB gamut and monitor colour spaces even though there are also many sRGB colours that cannot be replicated by the printer. We want to use Adobe RGB (1998) since it's gamut exceeds sRGB and includes almost all of the colors your printer can produce. ......even though some of these colors may not be visible on screen, by having them fall inside the working space gamut, the final print is more likely to have smoother and subtler tonal gradations.  The data exists in the image file, whether or not your monitor can reproduce it, ...that gives more image-processing "headroom".....to perform more image processing steps without creating posterization or other artifacts in your print".

It sort of makes sense to me Chris - I just wondered what you thought of it?

Annie

Offline chris.bailey

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Re: Printing/colour management
« Reply #4 on: 15:29:28, 19 March, 2017 »
Annie

It make sense to me too but if you search the web there are plenty of examples of printer manufacturers making claims about having wide gamuts that are not borne out in practice with many reports suggesting that sub £1,000 are unlikely to print much more than 50-60% of the AdobeRGB colour space. Home printer/paper combos tend to aim for slightly oversaturated, high contrast prints as that is what we are used to seeing from print labs. So some printable colours may well be outside sRGB but still within Adobe RGB.

For my RAW DSLR photos I bring them in using ProPhoto colour space (wider still than AdobeRGB), view them based on a profile for the monitor and then convert to sRGB for web use and convert to a printer profile for printing. The wide gamut of ProPhoto gives you plenty of headroom when doing edits and for things like HDR. The setup screen in Pixinsight is below, there is something very similar in Photoshop

For Astro I work in AdobeRGB, view based on a monitor profile and then convert to sRGB for web. The setup screen in Pixinsight is below, there is something very similar in Photoshop. Not all browsers are colour management aware so a photo on the web viewed in Safari can look different than one viewed in Firefox etc.

Chris
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Offline Annie

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Re: Printing/colour management
« Reply #5 on: 22:12:43, 19 March, 2017 »
yes Chris the color settings screen in Photoshop is very similar to the one you show for Pixinsight and I will use Adobe RGb (1998) for my astro work and set photoshop to handle color management. I can't find anything in my printer settings/profile to indicate whether it's going to override the setting for photoshop to handle color management and make it's own color adjustment other than something in print options which says: ' disable the colour profile setting of the application software'. I'm not sure what it means by 'application software'?  I guess I'll have to try printing and see what works!

I haven't used ProPhoto colour space for my Raw DSLR work but will give that a try also.

Thanks very much for all the information Chris.

Annie

Offline ChrisLX200

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Re: Printing/colour management
« Reply #6 on: 09:50:34, 22 March, 2017 »
Annie, did you not get the Canon Print Studio Pro add-in for PhotoShop? I found it makes life a bit easier as it takes control of colour settings and makes a bit more sense that trying to work with PhotoShop's settings directly..



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