create your material at the size at which it will be printed. Enlarging images in your
artwork can seriously degrade quality - or do as graphics professionals do, create your images oversize and do any retouching and
airbrushing before reducing them to the required size for printing.
For top quality printing photographs, drawings, scans
and all RGB and greyscale images should be created at 300dpi or higher. For mono line art use 1200dpi.
IMPORTANT: Simply increasing the dpi of an image in Photoshop will not improve quality - it's the original image that must be created at 300dpi in the first place.
We can still print images that are less than 300dpi but they may look jagged and pixilated.
As a rough guide divide the image dimensions (given in pixels)
by 300 to give the approximate 'litho' printing size. For example - a picture
of 1800 x 1200 pixels would be adequate for a printed size of up to 6in x 4in.
Pictures from digital
cameras are designed to be printed and generally reproduce very well
(much better than the equivalent film camera). As always though, the better the
equipment, the better the result.
If you are scanning hard copy originals please embed a colour profile within the image - Adobe RGB 1998 or US Sheet-fed CMYK are good all rounders. All images without a colour profile will be automatically converted prior to printing.
Flatten all layers and save images in whatever format suits you - JPG, TIF, PSD, EPS, PDF.
JPG (or JPEG) files are fine as long as you use minimum
compression and you don't alter and save the images too many times (you lose
quality each time you save).
BMP and PCX formats are ok, but tend to produce very large
PNG files are good quality - but they don't contain a colour profile so they have to be converted prior to printing.
Internet images: GIF format can only cope with 250 colours so they give inferior
results when printed - and most JPG images on the internet use extreme
compression which can cause colour shifts and blurriness.
Since JPG and
GIF are the most common image formats on the web, it follows therefore that
it's not a good idea to simply lift an image from someone's website - and
it's almost certainly an infringement of copyright.