Converting RGB to CMYK

[davidlower8]

Hi,

I am trying to get a question that has been discussed a lot, but the answer still eludes me personally. I am creating a logo pack for a client. I have started the document in RGB - but then converted to CMYK before uploading PNG, jpeg files. When opening the files they are still appearing in RGB. So even though I am converting the whole document via 'document setup' from RGB to CMYK - it still won't upload to CMYK for PNG or jpegs. I read in one comment this is default to affinity that they won't unpload PNG or jpeg in CMYK format. Is this really the case? How can I work around that? Or is it really that simple, for print ready work you just provide the client with a PDF and/of EPS file?

Thanks for the time.

[Gabe]

Hi @Davidlower,

I could not replicate this. See attached:

Have you got a different workflow? 

Thanks,

Gabe. 

[Old Bruce]

PNG and JPEG are RGB file formats, they are not CMYK. RGB = Computer Screen, CMYK = Printing Press.

An Affinity Photo or Affinity Designer document can be either RGB or CMYK and we can mix and match imported files but there is no way an image of any format can be exported to a nonexistent CMYK PNG because such a file does not exist. Apples and Oranges, both fruit but orange seeds won't grow an apple tree.

[lepr]

.

[davidlower8]

Hi guys. THANK YOU for all the feedback.

So knowing PNG can't convert to CMYK is useful. I am still having a problem however. When converting the document from RGB to CMYK and then exporting a CMYK jpeg file - I open that jpeg file and the blacks are still showing a blend rather than a 100% k value. So this is not giving a true black for printing. How do I fix or export it correctly so that the true blacks are exporting with 100% K value for CMYK? How do I also know this is happening when exporting as an EPS and PDF file?

Thanks for the help.

[Mithferion]

14 minutes ago, Davidlower said:

Hi guys. THANK YOU for all the feedback.

So knowing PNG can't convert to CMYK is useful. I am still having a problem however. When converting the document from RGB to CMYK and then exporting a CMYK jpeg file - I open that jpeg file and the blacks are still showing a blend rather than a 100% k value. So this is not giving a true black for printing. How do I fix or export it correctly so that the true blacks are exporting with 100% K value for CMYK? How do I also know this is happening when exporting as an EPS and PDF file?

Thanks for the help.

For a Rick Black, go this way:

C: 72

M: 68

Y: 67

K: 88

Best regards!

By the way, see the attached images. Both were exported from the same file, one with RGB profile and the other with CMKY profile.

[souacz]

I do not understand your problem... Could you look at attached video below screenshot? I prepared CMYK file and exported it as CMYK jpg and the black is 0 0 0 100. The problem is export CMYK file as RGB jpg because you can not attach embed RGB profile, only CMYK profiles are available. But when you convert RGB to CMYK you you must bring blacks to K100 before export because the color will change after conversion. You can see it clicking black element and checking color. It is for example 59 53 55 76 (depending on color profile). This is the case in every graphic software I use.

 

 

[Ballyshannon]

I do high end magazine/publication layout, and always have to convert client-supplied RGB jpg images/photos to CMYK in Photoshop for print. It's usually not a problem other than watching for color shift, especially blues and reds. Blue skies turn purple and reds go orange, both requiring correcting.

Personally, I always design client logos in 300 dpi CMYK from the start. That way, if they need it for print, they're covered. If they need it for web or other RGB based media, CMYK can easily be converted to RGB, usually without color shifts.

[davidlower8]

Ok so I figured it out due to mostly my own inexperience and stupidity. The problem I was having is RGB makes perfect black through blending multiple colours together. When I changed document to CMYK - obviously the CMYK tried to match to the nearest colour. As a result it also gave a black based on multiple colours. Normally this is fine but this particular project is for print (namely newspaper). As a result having a black made from multiple colours is poor practice for printing with newspapers beacuse you are involving 4 different colour plates to achieve the black. So I manually changed the black to pure 100 k value and that way the printing will use only the one black plate - therefore a much better printing output.

Once again thank you for all the tips and help. very enlightening.

[souacz]

Sometimes printers require that black is not K100, but it was mixed with CMYK. In the CMYK model, the use of 100 K as black gives in fact a graphite color. To get deep blacks up to 100 K, admixtures of the remaining colors are added. In standard CMYK printing for newsprint printing, the maximum paint coverage is from 160 to 260, for printing on offset paper up to 280, and for coated paper it is from 280 to 340. Each print shop has its own standards and recommendations in this regard. The optimal black in the Printing Room is 70C 70M 70Y 100K. Of course, the maximum permissible color saturation should not be exceeded.

[davidlower8]

On 11/1/2018 at 5:18 PM, souacz said:

Sometimes printers require that black is not K100, but it was mixed with CMYK. In the CMYK model, the use of 100 K as black gives in fact a graphite color. To get deep blacks up to 100 K, admixtures of the remaining colors are added. In standard CMYK printing for newsprint printing, the maximum paint coverage is from 160 to 260, for printing on offset paper up to 280, and for coated paper it is from 280 to 340. Each print shop has its own standards and recommendations in this regard. The optimal black in the Printing Room is 70C 70M 70Y 100K. Of course, the maximum permissible color saturation should not be exceeded.

Thanks for that nice explination. However it is my understanding that traditional printing - like for newspapers and similar - for best results you need to have CMYK 100k black. Like for our natonal newspapers, I would be very suprised if the blacks in those for the body content is a mix of different CMYK values. For anything else like brochures, business cards and booklets I agree a mix of CMYK will give better results for the black. Am I wrong in this thinking? At least this is what I have been taught.

[Alfred]

On 11/1/2018 at 9:10 AM, Davidlower said:

RGB makes perfect black through blending multiple colours together

Not so! RGB colours are obtained by adding together different amounts of red, green and blue light. Pure RGB black is what you get when there is complete absence of any light.

18 minutes ago, Davidlower said:

Thanks for that nice explination. However it is my understanding that traditional printing - like for newspapers and similar - for best results you need to have CMYK 100k black. Like for our natonal newspapers, I would be very suprised if the blacks in those for the body content is a mix of different CMYK values. For anything else like brochures, business cards and booklets I agree a mix of CMYK will give better results for the black. Am I wrong in this thinking? At least this is what I have been taught.

For graphics using CMYK process colour you might want to use a ‘rich’ black, but for body text you’re likely to cause registration problems if it appears on more than just the K plate.

[souacz]

It depends on the requirements of the printing house, I had the case that the printing house wanted pure text in the form of mixed colors. Mostly, however, the black text is best represented as K100