Computer Graphics with Photoshop - Removing grey cast after scanning with Photo Impact

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Removing grey cast after scanning with Photo Impact

Luke

2004-10-10, 12:14 pm

After scanning a B&W photo with photo Impact and my Memorex 48U
scanner. I get a grey cast over the photo and when i go to Print a
grey cast is left on the paper.
how do i get rid of that grey? TIA

Tacit

2004-10-10, 12:14 pm

>After scanning a B&W photo with photo Impact and my Memorex 48U
>scanner. I get a grey cast over the photo and when i go to Print a
>grey cast is left on the paper.

Most likely, there is no "grey cast"--the idea of a "grey cast" in a B&W photo
makes little sense. What you're seeing is the fact that the contrast is too
low.

The right way to fix this is to use your scanner software's advanced controls
to set the hilight and shadow point appropriately. If you don't want to re-scan
the image, use the Curves command to increase the contrast.

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Stuart

2004-10-11, 12:14 pm

Tacit wrote:
>
>
> Most likely, there is no "grey cast"--the idea of a "grey cast" in a B&W photo
> makes little sense. What you're seeing is the fact that the contrast is too
> low.
>
> The right way to fix this is to use your scanner software's advanced controls
> to set the hilight and shadow point appropriately. If you don't want to re-scan
> the image, use the Curves command to increase the contrast.

What about just using the "brightness/contrast" option, or does
adjusting the curves give a better result?

Stuart

Tacit

2004-10-11, 12:14 pm

>What about just using the "brightness/contrast" option, or does
>adjusting the curves give a better result?

The "brightness/contrast" command should not be used on any image you actually
care about. Photoshop's "brightness/contrast" and "color balance" commands are
only there for novices who don't want to take the time to learn Levels or
Curves and don't care about quality; they are "linear" commands, which means
they degrade the quality of the image by removing detail from the hilights
and/or shadows of the image.

Curves can do absolutely, positively everything that Brightness/Contrast and
Color Balance can do, but Curves is a "nonlinear" command; it does not degrade
image quality by clipping image detail.

--
Art, literature, shareware, polyamory, kink, and more:
http://www.xeromag.com/franklin.html

Stuart

2004-10-11, 7:14 pm

Tacit wrote:

>
>
> The "brightness/contrast" command should not be used on any image you actually
> care about. Photoshop's "brightness/contrast" and "color balance" commands are
> only there for novices who don't want to take the time to learn Levels or
> Curves and don't care about quality; they are "linear" commands, which means
> they degrade the quality of the image by removing detail from the hilights
> and/or shadows of the image.
>
> Curves can do absolutely, positively everything that Brightness/Contrast and
> Color Balance can do, but Curves is a "nonlinear" command; it does not degrade
> image quality by clipping image detail.

In retrospect I don't use brightness/contrast on images I care about, I
use it to better define a black and white scanned line drawing for
digitising.

Stuart

Tacit

2004-10-11, 7:14 pm

>In retrospect I don't use brightness/contrast on images I care about, I
>use it to better define a black and white scanned line drawing for
>digitising.

For an image that's intended to be bilevel (all black or all white), there is
no hilight or shadow detail, so the fact that the Brightness/Contrast command
clips hilight and shadow detail is irrelevant. :)

--
Art, literature, shareware, polyamory, kink, and more:
http://www.xeromag.com/franklin.html