QUARK 16 bit image/8 bit image

[worldsatwa]

How come when I go to 'file', 'get picture' in Quark Express 6, if the original is from a photoshop Tiff image at 16 bit channel, the photo looks great in Quark, but if it is saved as an 8 bit channel it looks really bad (jagged)
They both look just as good as each other in photoshop, but in Quark there is a huge difference.
This is a problem as 16 bit images are so large files.
Any answers?

 

[duncdude]

Very briefly... it all comes down to 'Binary'.

The picture you are looking at in Quark is only a preview. It is not the final printing file. This is why when you are opening the images in Photoshop for comparison they appear identical.

An 8-bit image can contain 2^8 = 256 colours (2 * 2 * 2 * 2 * 2 * 2 * 2 * 2). Any colour from this palette can be used for each pixel (picture element). The result is a fairly accurate appraisal of how the actual picture will print. 8-bit is a rather limited palette.

A 16-bit image can contain 2^16 = 65,536 colours (2 * 2 * 2 * 2 * 2 * 2 * 2 * 2 * 2 * 2 * 2 * 2 * 2 * 2 * 2 * 2) to describe the image. Any colour from this palette can be used for each pixel (picture element). The result is a very accurate appraisal of how the actual picture will print. 16-bit is a very large palette of colours resulting in an almost photographic quality preview.

Due to this the 16-bit preview will inrease the size of the file. This will simply result in a better display in Quark. It would be of benefit when printing to a non-Postscript printer which only uses the screen display to print from. Any Postscript printer will look 'into' each picture file and print them properly.

Regards
Duncan