Converting RGB to CMYK

Quality loss and harsh color when RGB converts to CMYK

Tony Bamonte from Spokane, Washington, USA, using Adobe Photoshop CS (8) with IBM, writes in with:

[Quote:] I am scanning vintage postcards for a book project. When I convert my scans from RGB's to CMYK's, which the printing industry demands, I lose the quality. They become harsh, unnatural looking and slighly blurry. They look great as RGB's. What can I do, or how can I adjust them to look their best. I'm scanning at 300 dpi. Thank You.

Reply:

Guess what: CMYK cannot reproduce all the colors you find in RGB. Those unmatched colors are referred to as "Out of gamut" -- therefore when you convert from RGB to CMYK, Photoshop automatically modifies all the colors in the file to their nearest CMYK values -- which can cause the troubles you're experiencing.

Ideally, your best bet is to actually scan in CMYK. See if your scanner has that option. If you do a lot of this kind of work you would be well served to purchase a scanner (or scanning software) with CMYK capabilities. If you have just a few to scan, check the local service bureau or photo store. If they can scan it for you, they usually don't charge much.

One way to attempt a closer color match is to use the Custom Proof setup.

Choose: View > Proof Setup > Custom

You can toggle off and on the "Preview" button to see before and after.

Experiment with the Profile and Intent pull-down menus to try different settings.

If you are unsuccessful, then Choose: View > Gamut Warning
The colors indicated are those which will be affected. If they are simple and appear not to influence the entire file, you can attempt correcting them using the Sponge tool (Tap O) with Desaturate from the Mode pop-up menu.

Now begin attempting to pull the colors back into gamut by lightly painting over the out-of-gamut colors with the sponge tool. As they come into gamut their color will return. If desaturation is too severe, the colors will go dull, you must be careful.

Select View > Gamut Warning again to re-proof the color.

You can also make a SELECTION of all out-of-gamut colors using Select > Color Range > Out-of-gamut. Using this will select those color areas to restrict your editing to just the selections.

Ideally, your best bet is to actually scan in CMYK. See if your scanner has that option.

Bottom line: RGB suffers a loss of color when converted to CMYK. Use the above to get "close" to a desirable image.

Comments

[joe]

In photoshop, the code of CMYK is different from the online converter. Anyone knows which one is correct?

[Gary]

I am writing to ask what is the best software for converting images from RGB to CMYK ? Does Photoshop CS4 do it and what do you think of that software? What is your best recommendation?
Thanks

[R henderson]

trying to change Artwork, should be created in 300 dpi but i did it in 72 how do i convert to 300 with out causing distortion of the image please any help would be appreciated

[Muradu]

sir ihave problam in scan time when i scan book page black color into 4 color i want black sprat

[Michael Collin]

Hi, I am currently having problems with an image that was created as an RGB file in Photoshop. I have converted the image to CMYK and adjusted all of the colour values so that they are pretty much bang on the original. The trouble starts when I convert the CMYK files into JPEGs or view the Photoshop file in a different viewing programme because these images now look completely desaturated, as though I had converted RGB to CMYK without altering anything, if not worse. When viewed in Photoshop the CMYK version of the original looks the way I want it but no matter what I export it as it looks totally washed out. If anyone could shed some light on this problem I would be most grateful.

[Saba]

hi i facing text color problem in photoshop, when i type a text in light color on a black image it show red but if i type in a dark color it don't show this problem can you please help me how i work with it, i've done everything but result is still zero

[Roby]

Sir,
is there any new technology like printers or something to get the exact color from RGB when we change it into CMYK?And i am realli very happy to see a website which we can ask questions and espescially in the field of designing.

[Roby]

sir,even i am facing the same problem so wht can i do to change the RGB color to CMYK?And when i change it there is a very big diference in the image,so wht can i do to give a visiting card for printing?do i have to save the RGB into jpeg and give it or nothing can be done?
thanks a lot

[Emad Baqer]

hi
i also need help if i converted my work (half way) from rbg to cmyk
well the color vallue be harmed in printing process
NOTE: i am coloring with sampel color of a cmyk mode created for my own paleta

[chris]

Hi.
Yes it's a pain, I need to produce design work for print companys that
are all using mac. I find the best solution is to go into there
studio and ajust the contrast and saturation when they have
loaded it into the mac! Have Adobe not spotted the huge profit
that could be made from the solution to this problem? If such
a pluggin was avalible I would buy it!

[Rid]

I also have problems like that?

[Clayton Giovanni]

Hey Guys/Gals

RGB Solution..If you have direct access to your printer..try just sending your files AS IS in RGB and NOT messing with them? You would be surprised..most printing machines have a HIGHER DEGREE of good conversion on the fly from RGB to CMYK. I didn't believe it myself till I compared and was WOWed!..

So..if you have a HIGH LEVEL RIP DEVISE OR A DARN EXPENSIVE COLOR PRINTER...Try sending RGB AS IS?!?...BETTER YET..because of profiles and all..SAVE YOUR PICS AS .EPS and then place in your files to send to a printer.

Have noticed if i print from photoshop all is good..but printing same 'tif/jpeg' out of a layout program really messed with colors. YEAH, I KNOW it's color management..but for now..I just send .EPS Pics...and they are great!

Laterz!!!

Clay