colorspace question

[transoptic]

I work with RAW files and usually save images for the web, although sometimes I need to send images to print.

Now I understand that sRGB is optimal for web viewing, but should I do all my editing in a larger gamut? AdobeRGB or Profoto, for example?

[Swampy]

Edit in RGB for print save as RGB (300 DPI). Convert to CMYK and save a TIFF under a different file name for hand off to the printer.

[skydog]

Great timing for this thread...

I've never had to deal with CMYK since most of my work is with photos, but recently I was asked to design a business card for a friend. Enclosed is the back the the card in both RGB and CMYK. Both the customer and myself like the RGB, but we question the difference and darkness of the CMYK. I did has Swampy suggests above, but I wondered if I should have designed in CMYK so I know the color I am dealing with? But then I guess what I see on the monitor in CMYK is not what I would get when we go to print? Does calibration of the monitor take care of this?

[transoptic]

I wasn't talking about CMYK vs RGB... I was talking more about color profiles such as sRGB or Profoto.

[skydog]

Sorry bout that...I guess I picked that up from Swampy's response. Hopefully someone can give me a quick response to my question...

[pixelzombie]

from what i understand and i could be wrong here, but you only need adobe RGB if your subject mater can actually use the wider gamut and if you have an output device that can handle such a wide gamut...

[DWThomp]

I generally do my RAW conversions to AdobeRGB and the corrections in it. One of the labs I use for prints wants the file in sRGB so I do the conversion as the last thing. Also, any save for web gets converted to sRGB.

[Swampy]

To answer Skydog's question. I have a tutorial on Color Shift to help explain why it happens and although it talks about inkjet printers, the theory applies to high end commercial presses as well. You can get a feel for areas in your work that are going to shift when printed by going to View>Gamut and turning on the gamut warning. A highlight color (chosen in Photoshop Preferences) will designate the areas that will be affected by color shift. Also, your color picker will be limited to the areas that fall within the printing gamut.

[mquest]

I suggest that you do your editing in AdobeRGB, then you have a good original for conversion to both sRGB and whatever CMYK profile you want.

[BobJones]

Forget about CYMK unless you are doing prepress and sending this out to be printed on some kind of printing press.

When it comes to color spaces, bigger isn't always better. When it comes time to print, the image will have to be converted to 8-bit depth (I'm not aware of any printer that accepts 16-bit at this time) and you'll find that larger color spaces are not as smooth in the transitions from one step value to the next as a smaller color space. You can introduce banding in areas of subtle color variations. And, the wider the color space, the harder it will be for to work accurately with the image on the monitor.

And, just because you use a larger color space, it doesn't mean that you will actually make use of the full gamut possible. Unless you tend to shoot highly saturated images, it's likely that the majority of colors in the image will fit within sRGB.

It makes the most sense to work in Adobe RGB or another larger color space if you are printing your own prints. If you are sending your photos out to a photo lab for printing, the vast majority require sRGB.

My preference is to use a working color space of Adobe RGB and print using my own printer. I'll convert to sRGB when necessary. But, I'll work natively in sRGB when I'm working with subtle color graduations or where it makes sense to do so.

[julie_swiderski]

does anyone know why a printer would prefer a grayscale file over desaturated rgb file for printing black and whites on 4 color press?

[pixelzombie]

a desaturated image will look very flat in certain areas

[julie_swiderski]

im having quite the opposite effect. the grayscale image is flat and muddy with no contrast, the desaturated rgb file has much more tonal range and contast, with much richer blacks.

[ImBET]

When printing a "neutral" gray image. A 1/c Black "grayscale" file will stay neutral due to the black only. When printing a neutral gray image made up of 4/c a straight conversion from rgb to cmyk will give you full cmy neutral and a skeleton black (dark shadow end only). This will be tough to produce as neutral on press because of ink balance sensitivity and other press conditions. A custom profile or action build to create a lighter perhaps shorter ranger cmy and a heavier longer range black would help on press to keep neutral but also have some extra depth and detail.

[Kermy]

Use prophoto or adobe 1998. prophoto preferably as this has the widest gamut. but you need to do this from the start when you convert your raw files. theres no point assigning a profile once its converted. and once you have done your retouching you will need to convert to cmyk. what you should do is go to 'edit' then to 'convert to profile' and select a Fogra labeled cmyk profile. Fogra 39 is the best one out there at the moment. And what this does is provide the best rgb to cmyk conversion possible, as some colours don't convert to cmyk too well. you loose vibrancy, especially in reds. so you might have to slightly tweek the cmyk when its converted. But by choosing the Fogra engine for conversion you are minimising the difference that exists between rgb and cmyk...

[julie_swiderski]

Imbet,
..."A custom profile or action build to create a lighter perhaps shorter ranger cmy and a heavier longer range black would help on press to keep neutral but also have some extra depth and detail."

im forgetting how, but we used to do this, ghosting back each channel and pasting into black, and they came out beautiful. im sitting here working on this now trying to remember how i did it, it's been so many years since i worked in prepress using cmyk. we're using rgb files here and our printer converts them.

Kermy,
our photographers do use prophoto and yes they come out beautiful but the files im using are adobe 1998 (our photographers didn't shoot the material we're using) I'll see if i can find that profile Fogra 39

thanks!

[SilvaFox]

Originally Posted by ImBET

When printing a "neutral" gray image. A 1/c Black "grayscale" file will stay neutral due to the black only.

Grayscale B/W's do not print neutral. They print thin and ( depending on what paper is being used), toward green.

You would think they would print neutral, but not the case.

OK. Sorry. Back to profiling.

[ImBET]

When printing on press the black (1c grayscale)will be as neutral as your black ink. When printing on an older inkjet your black (1c grayscale) will rip into a file that is made up of that ink set, and mostly looks green. We have an Epson 7900 which prints blacks much more neutral than our old 4800 and 9600

[shift studio]

Originally Posted by julie_swiderski

Imbet,
..."A custom profile or action build to create a lighter perhaps shorter ranger cmy and a heavier longer range black would help on press to keep neutral but also have some extra depth and detail."

im forgetting how, but we used to do this, ghosting back each channel and pasting into black, and they came out beautiful. im sitting here working on this now trying to remember how i did it, it's been so many years since i worked in prepress using cmyk. we're using rgb files here and our printer converts them.

I came up with a similar technique because I was sick of seeing casted 4-colour black and white images.

Starting with a real nice looking monotone-RGB or Grayscale image, try this:

1. Load the luminosity as a selection (opt+cmd+2 in CS4)
2. Save selection as an alpha channel
3. Create a new CMYK document with same size/res
4. Fill a layer with a rich, neutral, black-controlled black (40/31/29/100 for example)
5. Duplicate the alpha channel into the CMYK image
6. Load a selection from the alpha channel
7. Fill the selection with white on the rich black layer
8. Create a curves adjustment layer, set blend to soft light.
9. Make an s-curve and adjust to taste


This will give you a monotone cmyk that is really neutral, because the black is so much stronger than the other colours. It will be rich because it contains all for inks. It'll also make sure there is black in all tones instead of just shadows.

Its really pretty good. Give a try. BTW I don't know how this will look on an inkjet, just good on press.

--Shift Studio.