Digital BW, The Print

On 3/19/02 2:01 PM, "Paul Roark" <paul.roark@...> wrote:

> The very last step I now take is to change the size of the image in
> Photoshop from the scanner's native resolution to my print size at 360 dpi.
> 
> When I check the histogram there is no combing.
> 
> I have not analyzed prints to see if I can see any difference.

It is obvious why this eliminates combing. When you resize, Photoshop
interpolates between the discrete values that represent the teeth of the
comb to arrive at the pixel values for the new image.

For example, let's say you have two neighboring pixels, one with value 150
and one with value 175, and the image displays combing between these two
values. Downsampling will probably produce a pixel in this region of the
photograph with an intermediate value of around 165. Thus you now have some
pixels with the intermediate value where previously there were none.

The absence of combing in the resized image is not a sign that it's
'better', it's a sign that information has been lost. You could also
eliminate combing by applying a 1 or 2 pixel radius gaussian blur before
printing, but I don't suppose anyone is doing that.

-- 
John Brownlow

http://www.pinkheadedbug.com