[jennverr]

Hi all

I have a b+w photo I need to make a CMYK file from. So, here is what i did, went to Pshop, selected mode: CMYK. then saved it. The question is, I am not sure of do I need to save it as a jpg or tiff or what? and then does the compression stuff make a difference? I honestly had no idea what it was asking me, so i just selcted "none". Is there anything else I need to do here?

Also, when viewing the CMYK in picture viewer after doing this, it looks very odd, and almost has a bluish cast to it. I am hoping it will look different to the people it's going to when viewed in a proper program?

Thanks!

[johnmflores]

CMYK is Cyan Magenta Yellow Black and are the four colors used to reproduce photos and artwork in most published materials - magazines, color newspapers, billboards, brochures, etc... Many color desktop inkjet printers use CMYK (or some variant of CMYK) as well.

Computer monitors and other digital devices, on the other hand, use RGB (Red Green Blue). So if you view a CMYK image on an RGB monitor there will be some color shifting.

If you need to save a photo as CMYK, I believe that Photoshop .PDS and .TIF are your most popular options; saving as JPG will bring you back to RGB.

So save your photo as a CMYK tif file and you should be fine. Compression is ok, esp if it is a large file that needs uploading.

Hope this helps...

[Ron Kruger]

John,
My agency wants aRGB, which is CMYK, but they want them as JPEGs. When I shoot, or convert, a RAW files in aRGB, the converted JPEG from it also has a CMYK color space.
By the way, I've learned the best way to convert a RAW sRGB to aRGB is in the Pentax Lab...much better job than PS.
Jen: I don't understand: "I have a b+w photo..." Color can be converted to b/w, but I didn't think b/w could be converted to color.
If your monitor is calibrated, aRGB should look fine. If not, they will look strange.

[jennverr]

okay, thanks all. Ron, the photo was taken w. black and white film, then scanned. IT was actually in RGB in pshop when i opened it, but obviously no color. so i just converted to CMYK. I think I will send both the jpg and tiff version just in case.

thanks!

[lyzan]

Use Adobe PS convert to profile.

When converting an RGB pix to CMYK, one must know what kind of CMYK color space your printer requires. If you don't know, you must submit your pix in RGB and let them do the separation/conversion to CMYK which guarantee correct conversion according to their CMYK profile, otherwise you will have unpredictable output.

If your printer just ask you that they need CMYK without giving you their profile or ask you to convert to specific CMYK ICC standard profile, run from that printer. They don't know what they are talking about.

Just an opinion.

[jennverr]

Hi lyzan

yes they just said CMYK, 300dpi, 8 inches.

[jennverr]

so the file size is 22mb as a CMYK tiff, and about 16mb as a tiff with LZW compression. these seem like rather large files, is that normal?

[lyzan]

Then run from that printer...

Try to ask them what kind of CMYK profile to use. In ISO standard for example there are ISO coated V2, ISO Uncoated, ISO newspaper, etc. If you have PS, look at the color settings, CMYK. You will notice there are lot of choices. And each choice will have different outcome if you will try to convert your pix to each CMYK profile in there.

If your printer is a digital printer, ask them of their in house CMYK ICC profile otherwise find another printer.

Yes the file size is normal if you are going to use TIFF. If you can deliver your pix with that file size then it's not an issue. However, you can always save it in PDF format using high quality printing specification. Or you can even save it as JPG using high or maximum quality compression.

[Wombat]

Like Ron, I don't understand what you're trying to do. As others have explained, CMYK is a colour space. I don't see how you can convert a scanned b&w photo to a colour one. Is the printer expecting a colour photo from you? Is s/he aware that the source photo is in b&w? You might want to clarify this before you go to a lot of trouble.

[jennverr]

Like Ron, I don't understand what you're trying to do. As others have explained, CMYK is a colour space. I don't see how you can convert a scanned b&w photo to a colour one. Is the printer expecting a colour photo from you? Is s/he aware that the source photo is in b&w? You might want to clarify this before you go to a lot of trouble.

Hi Wombat,

There is a magazine that asked for a CMYK version of a photo I submitted to them. The photo was a scanned 120 b+w film, but when opened in PShop was, RGB mode. So i just switched it over to CMYK, adjusted the size to what they wanted, and sent it off. I just told them if there was an issue with the file to let me know. *shrug*. When i came to work and opened the CMYK file on my mac at work, it looked fine, like a b+w photo.

[johnmflores]

John,
My agency wants aRGB, which is CMYK, but they want them as JPEGs. When I shoot, or convert, a RAW files in aRGB, the converted JPEG from it also has a CMYK color space.

You're right, Ron. I've been in the web world so long and using Photoshop's Save for Web (RGB only) that I forgot the other options.

Hi Wombat,

There is a magazine that asked for a CMYK version of a photo I submitted to them. The photo was a scanned 120 b+w film, but when opened in PShop was, RGB mode. So i just switched it over to CMYK, adjusted the size to what they wanted, and sent it off. I just told them if there was an issue with the file to let me know. *shrug*. When i came to work and opened the CMYK file on my mac at work, it looked fine, like a b+w photo.

When you converted to CMYK, it may have simply mapped the grey tones to the black (K) channel. But it's just as likely that the conversion process is creating greys from a combination of CMYK. This is done (I think) to provide greater and more subtle tonal range - a smooth gradient from white to black instead of banding and stair-stepping between tones.

If you open up the CMYK file in Photoshop, point to different parts of the photo while looking at the Info panel. There'll you'll see the values of CMYK used to create a particular grey tone.

If the magazine is good, they'll do what they need to make sure that your photo doesn't end up with a color cast due - a bluish tone due to too much Cyan, a purplish tone due to too much Magenta, or a sepia-like tone due to too much Yellow. They do this stuff every day and should know the press and the paper and the inks that they are working with.

[jennverr]

You're right, Ron. I've been in the web world so long and using Photoshop's Save for Web (RGB only) that I forgot the other options.



When you converted to CMYK, it may have simply mapped the grey tones to the black (K) channel. But it's just as likely that the conversion process is creating greys from a combination of CMYK. This is done (I think) to provide greater and more subtle tonal range - a smooth gradient from white to black instead of banding and stair-stepping between tones.

If you open up the CMYK file in Photoshop, point to different parts of the photo while looking at the Info panel. There'll you'll see the values of CMYK used to create a particular grey tone.

If the magazine is good, they'll do what they need to make sure that your photo doesn't end up with a color cast due - a bluish tone due to too much Cyan, a purplish tone due to too much Magenta, or a sepia-like tone due to too much Yellow. They do this stuff every day and should know the press and the paper and the inks that they are working with.

Thanks I hope that they will adjust it if there is a blue tone. Because i did see a blue tone on it, depending on which program i used to open it. i also did notice that there is more of a range of greys in the photo once converted to b+w, but i hope that doesn't mean it will look extra muddy when printed. i guess we will see when it comes out!

[lyzan]

@jenverr,

Whether you have a "color" RGB or "grey/bw" RGB, the conversion to CMYK will depend on your CMYK ICC profile. And I don't think they will adjust your photo, otherwise they will be happy to accept your RGB photo. When a printer ask their customer to submit in CMYK without guiding their customer to what they needed, that printer is trying to escape from their responsibility in color separation. If you found later on that the colors are unacceptable, they will simply tell you that it's your separation not theirs. If you want a good black-n-white, use PS features. There's a lot of technique to produce an excellent range of tone from RGB to black and white.

The outcome of your submitted photo will depend on how good your printer is. Most likely it will be bluish.

[panoguy]

If the magazine is good, they'll do what they need to make sure that your photo doesn't end up with a color cast due - a bluish tone due to too much Cyan, a purplish tone due to too much Magenta, or a sepia-like tone due to too much Yellow. They do this stuff every day and should know the press and the paper and the inks that they are working with.

Or worse, they do this stuff every day so don't give a crap about what it looks like!

Most likely you won't see a single color cast over the whole image, but rather different color casts at the highlights/ midtone/ shadows. The reason is that the CMY colored inks are all being dropped down with Black (K), but the dots are not in the same places due to the "screens" used to avoid overflow, which are based on the density desired.

In general, CMYK printed black/white images have shadows that will tend to run brown (magenta floating on the black), and midtones blueish (cyan peeking through), and highlights all over the place based on what channels are clipping first. Mitigation of these is a tough separation job, and most places outside of fine-art bookmakers don't put the attention into it. If you're lucky, they'll push it to grayscale (and empty the CMY) and let their black plate do it all (a little weak in the shadows, but no casts!).

I've frequently done custom separations where I pump up the Black and tone down the CMY using brightness/contrast on each individual channel - but I've worked with 4-color seps for decades and I know the printing processes backwards-forwards.

Bonne chance!