Original copy material - continuous tone original

A continuous tone image is an image like a silver photograph or a painting where there is a continuous range of tones from black through various shades of grey to white. We might need to copy this because it is the only image in existence - the negative might have been lost or miss-placed.

 

Black and white photographs published in books appear to have a continuous range of tones. However this is an illusion which is created by thousands of black dots.

Detail of a course half tone screen image. In the printing industry photographs are scanned with a half tone screen, which breaks the image up into a series of dots that can pick the ink up and pressed onto the paper. In the black areas the dots are closer – in the white areas they are further apart.