rgb vs cmyk

[vengab]

Hi all,

I have an Epson RGB printer and the option of downloading say a 1.53MB RGB file or the same image in CMYK is 4.28MB

Is the reason the CMYK file is bigger (file size not dimensions) because it is 32 bit as opposed to the 24 bit RGB?

I want the highest quality image for printing so am I better off just getting the RGB file or the CMYK and then converting it to RGB?

[Doug Nelson]

CMYK has one more channel than RGB, so will be larger.

Sending a CMYK file to an Epson printer requires the driver to convert it to RGB, so better to convert it to RGB yourself.

[vengab]

Thanks for the reply Doug but do you think the considerably smaller file size RGB option of the same image that I have access to would be sufficient, or should I go to the trouble of downloading the CMYK and then converting it?

Download and print would by far be easier but would I be sacrificing quality?

[Doug Nelson]

One extra channel would not explain that size difference. The CMYK file is obviously a higher-resolution file. However, on an inkjet you really won't see much difference after about 200ppi.

Even 4MB for a file destined for print is tiny. If there's not a lot of blue in the image, try the CMYK (blue is the weakest link). Download them both and compare the resolutions.

In answer to your original question, 32bit would not enter into it, that's a different thing than when we discuss 8 and 16bit files. All 32bit images are RGB (at least in Photoshop).