Monday, February 7, 2011

RGB vs CMYK conversion

CMYK versus RGB in Printing

Important information regarding RGB and CMYK! Applicable when printing in full colour(CMYK).

When supplying digital files for full colour printing, it is important you supply images and graphics in the correct mode or colour space. Many software programs give you the choice to work in either the RGB or CMYK mode..

RGB stands for Red, Green and Blue which are the primary colours of light. Scanners and digital cameras generally create images using combinations of the three RGB colours. When you save a scanned picture, or image taken with your digital camera, it normally will be saved in RGB mode unless otherwise specified. In addition, computers display images on the computer screen as RGB colours.

Printing presses print full color pictures using a different set of colors than RGB. Generally, full colour images are created using the primary colors of pigment: Cyan (blue), Magenta (red), Yellow and Black - otherwise known as "CMYK printing" or "4 colour process". By combining different percentages of the 4 CMYK inks, the illusion of continuous tone in images is created.

At some stage in the design process, your images must be converted from RGB to CMYK in order to print them on a printing press. Unfortunately not all colours in the RGB spectrum can be replicated in CMYK. Such colours are said to be "out of the CMYK color gamut". When converting from RGB mode to CMYK mode, software programs get as close to original colour as possible. Some colours convert very well whereas others do not. Below is an example of colours that do not convert well from RGB to CMYK.

RGB Image CMYK Image

Do not be alarmed by the example above, as most photographic images usually convert quite well. Below is an example of converting a photograph. You can hardly see a change in colour. Generally, it is in extremely rich and vibrant colours where you may see the most colour shift.

RGB Image CMYK Image
Please convert all images and graphics to CMYK prior to sending your files to us. You will have more control over the appearance of your printed piece as you will see how the images look once they are converted. If need be, you can always adjust the image slightly after conversion to more closely achieve the desired colour. If we receive RGB images from you, we will do a standard conversion to CMYK, however our results may vary from yours.

For best results, we recommend working in CMYK mode whenever possible. Some applications like Photoshop and Illustrator actually allow you to work in different modes so be sure to choose the correct one!

Thanks to I.P. Impressions In Print Ltd. Vancouver, British Columbia Canada for the info.