I ran into that problem when I was designing my web page. The pictures
were resized, stretched a little, brightened, and the quality was
reduced so it wouldn't take too long to download. The end result was
awful. After just a couple steps, the digital artifacts started showing
up. I just figured it way my free Photoshop program (you get what you
Don Cox wrote:
> On 11/07/07, phillip holmes wrote:
>> I know you weren't. That was merely an "amen" for Bob. Most decent
>> ADCs can give good results, if they are used correctly. That's why I
>> don't like those "restorations". They "put lipstick on the pig" and
>> the result is unacceptable for me and the pig.
>> There was a great article about Pro-tools a while back. It explained
>> how all that manipulation in the digital domain gives such a bad
>> sounding product because every manipulation of the original signal
>> looses bit depth (or something like that---I'm an idiot about
>> digital). Phillip
> If you have access to Photoshop, you can see a visual equivalent.
> Load in a color photo, ideally one that is too dark. Go to
> Image->Adjust->Levels (or "Adjust Lighting->Levels" in PH Elements).
> You will see a histogram showing 256 levels of brightness.
> Adjust the sliders, which is the equivalent of adjust levels in audio,
> so that the photo looks better.
> See how the histogram breaks up - there are no longer 256 levels. The
> gradation is now jumpy.
> This is because, to change levels, the computer must map some pairs of
> levels onto single levels. The more steps you have to start with, the
> less trouble this causes.