Converting CMYK to RGB in photoshop

[baruke]

Hello!

What's the best way to convert a photoshop document from CMYK to RBG? (I am aware of Image-->Mode-->RBG Color)

I just want to do this process without causing damage or losing image quality!

Here is more info about my documents:

I am working with 5 by 7 inch PS docs that have clipart PNGs on them. I have arranged the PNGs and merged them into a single layer.

Do I have to flatten my images first? This wouldn't be the end of the world, however, I would like to avoid flattening if possible, so that I can save my merged PNG file with a transparent backround (I was only using the 5 by 7 as a size template). Did my PNG layers become CMYK like my document once I merged them?

Thanks!

[davescm]

Hi

Never use Image mode to convert. Use Edit > Convert to Profile and convert to the specific RGB color profile you want to use.

Similarly, there is no generic CMYK. So if your intention is to end up in an RGB profile do not start your document in a CMYK profile. You should only be working in CMYK if you know exactly which CMYK profile you will be using on the printing press.

When you imported your PNG files to layers, the images they contained took on the profile of the main document. That would have been through conversion (correct) or assignment (incorrect) depending on how you set your colour settings in Photoshop.

Converting to another profile without flattening could cause changes in the way the layers blend together - hence the warning.

Any conversion can involve a colour change if the colours used in the document are outside the gamut of the new colour space into which they are being converted. Whether that applies to your document I cannot say as it depends on teh actual colours used within it and the colour space from which and to which the conversion is taking place. You can use view > Proof set up and View >Proof colours to simulate the conversion, but even that depends on the capapbility of your monitor.

Bottom line is, if you know you are going to end up in RGB then start your document in an RGB profile. In Edit colour settings - set your policies to Preserve embedded profiles and you will get a warning message asking you to convert if there is a mismatch when importing.

Dave

[baruke]

Thanks! My situation is a little complicated, as I unfortunately already made many documents (wedding invitations) in CMYK, as they will need to be eventually printed. The third party app I'm using where customers can edit the names in their invitations, wants my documents to be in RGB. So I am trying to now convert to RGB, but I don't want quality to be lost of the third part app needs to convert back to CMYK when they export the documents for the customers to print 

[davescm]

You say you are working in CMYK as the invitations will eventually be printed. Are you working in the specific CMYK space for the printing press you will use. There is no generic CMYK and if you are not sure you should start and work in RGB then either do a final conversion to CMYK or let the printer do it for you. Converting from one CMYK profile to another is not good practice.

Dave

[jane-e]

"I would like to avoid flattening if possible, so that I can save my merged PNG file with a transparent backround ... Did my PNG layers become CMYK like my document once I merged them?"

Hi 

Dave gave an excellent reply but I don't see where this part is addressed. This is in addition to all that he said.

• You do not have to flatten your image. If you do flatten it, you will have one Background layer, which cannot be transparent. Merging layers will keep the transparency. I think you have already merged the PNGs together a single layer?
• PNGs do not support multiple layers.
• The entire Photoshop document will have the same color mode (CMYK, RGB, Grayscale, etc.). It's not layer by layer. As Dave said, when you combine images, they will take on the profile of the main document.
• It's generally not a good idea to convert from RGB to CMYK and back to RGB. The conversion should be done once.

~ Jane

[c.pfaffenbichler]

Related to the last two points:

One can alleviate those issues by placing RGB Smart Objects in CMYK images and their contents will, if the containging document should be converted again, converted anew based on the original data. 

Naturally they need to have their proper profile embedded, 

[c.pfaffenbichler]

»I would like to avoid flattening if possible«

You need not flatten an image for conversions if you don’t want to but you should be aware of what you are doing and that a layered CMYK-image can not necessarily reproduce the apearance of a layered RGB-image. 

In this example the issue is a simple neutral transparent »shadow« and it is because in CMYK there is no »true black«. 

In RGB »black« is 0/0/0, but in CMYK it is, depending on the color space, some combination of values (in this case 87/78/65/93).