What color format should be used to create a logo: CMYK or RGB? (It would be used for both printing and for screen)
You should supply both.
Ideally you should supply screen and print versions in RGB and CMYK and in vector and bitmap formats.
It completely depends on the situation and requirements but an example of formats to be delivered could be something like;
- JPG (RGB - high res & low res)
- PNG (RGB with transparency - high res & low res)
- SVG (RGB)
- PDF - (CMYK)
- EPS - (CMYK)
- AI - (CMYK)
There will normally be variation as well (e.g. Full color, black & white, with/without text etc) and there could be spot colors to take in to account and any specific format requests.
First of all RGB and CMYK are not standarized values.
I always mention one fast exercise.
Take a cyan watermark and draw a line on a newspaper and on a good quality magazine.
You will have a bright color on the magazine but a dark color on the newspaper. The ink is exactly the same, but the color is totally diferent.
A color profile, besides giving you the ink values (Cyan on this case) gives you the standarized conditions on where that amount of ink will be.
You do not define a cmyk or rgb value without a color profile.
So you first need to define a color profile and after that define a cmyk or rgb color.
The original question
What color format should be used to create a logo...
This will depend on the main aplication. If it is a web based logo, with only some ocasional printed aplications you could go for an RGB based image. But keep in mind that the printed version could look dull.
But if printing is important you define a CMYK color first, then for the RGB aplication you know you can't use veeery bright colors.
Normally you use a coated color profile to design. They are brighter than uncoated.
Or use some spot colors
In theory theese are more standarized colors. If your base logo has not gradients, but solid colors it is a safe bet. The drawback is that you have a more limited palete.
Normally you do not provide just a isolated file.
You should prepare some basic brand manual where you include not only the base files, but some adaptations.
Black and white? Only white as negative? Usage on bright white? usage with colour background?
You need to adapt thepending on the aplication.
A direct RGB red to CMYK could give for example some like this: C0M95Y92K0
There is nothing that stop you to define that CMYK value as C0M100Y100K0.
So at the end you need to design in a more integral way.
So in this manual yes, now you should include some files, some in rgb with the correct profile, some cmyk, with the correct profile, if you used it the pantone values.
In designing a logo, you should always start with CMYK. The reason being that CMYK has a smaller colour gamut than that of RGB.
The reasoning behind this is that when you are converting from CMYK to RGB to provide the logo for screen (eg. websites), the colours would have an unnoticeable shift in colour, if any.
On the other hand, if you start creating the logo in RGB, and then convert to CMYK for printing purposes, such as a commercial printing press, you are more likely to have a colour shift that is very noticeable, compared to the original.
In regards to the format of the logo, it is advised to create it in vector format. This will allow you to alter the size without affecting quality.
Bitmap is all about pixels, and as you enlarge it, it tends to try to fit additional pixels to fill in the gaps (sort of breaking each pixel into smaller pixels as you enlarge it). This process may degrade the logo.
Vector, on the other hand, is a filled shape; as it gets larger, it maintains the same look.
Now, whatever the format that you will end up using is only a bi-product. Your initial step should always be vector CMYK.
Final thought: Having a vector CMYK logo provides for an extended array of possible conversions without affecting quality or colour.
It should be CMYK and some prefer the use of Pantone colors to accurately convey the colors you intend to use in the logo.
The reason why it should be CMYK is that RGB has a much larger array of brighter colors, which when printed will not come out the same.
Short answer, CMYK or Pantone spot colors.
RGB is for web but CMYK is for printing & t-shirt printing
if you post cmyk to web it will convert to rgb and (or the opposite) look bad and poor colors
also rgb work with (jpg & png & svg) but on the other hand cmyk is for (eps & pdf & ai)
so if you create logo to post it to the web (website,facebook page,etc)use rgb
but if you want to create it to print it on t shirt on submit it to brochures posters etc and print use CMYK
I hope i helped you