Photoshop can’t modify a jpeg file. What is going on?

LE
Posted By
Leonard Evens
Jul 2, 2007
Views
493
Replies
3
Status
Closed
I am trying to enhance some pdf files produced by scanning documents. One method is to use Adobe Acrobat, Standard Edition, to extract images from the file. I get a bunch of jpeg files, one for each page. I opened one such file in Photoshop and increased contrast by using the threshold adjustment or levels. But when I clicked OK, the image goes back to what it was.

Can anyone tell me what is going on?
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R
ronviers
Jul 2, 2007
On Jul 2, 3:07 pm, Leonard Evens wrote:

when I clicked OK, the image goes
back to what it was.

Can anyone tell me what is going on?

Hi Leonard,

At what point in the process are you clicking OK?

Ron
LE
Leonard Evens
Jul 2, 2007
wrote:
On Jul 2, 3:07 pm, Leonard Evens wrote:

when I clicked OK, the image goes
back to what it was.

Can anyone tell me what is going on?

Hi Leonard,

At what point in the process are you clicking OK?

Ron

I make the adjustment in the appropriate adjustment window. The change appears to be made in the image window, but when I click okay in the adjustment windows, the image window goes back to looking as it did before the change.

I’ve investiagted further, and it make be that a change has actually been made, but that the display window is not showing it because what it shows is some smoothed version of the actual image file.

In fact, under Linux, using ImageMagick and the Gimp, when I look at these jpeg files, they look awful. Apparently the Adobe Reader is doing something with them when displaying which is different than just a default exhibit of the image. And Photoshop may be doing the same thing with such a file.

But all of this is just guesswork.

Anything that might help me with my ultimate aim—to enhance readability of pdf files produced from scans—would be appreciated.
R
ronviers
Jul 3, 2007
On Jul 2, 6:11 pm, Leonard Evens wrote:

Anything that might help me with my ultimate aim—to enhance readability of pdf files produced from scans—would be appreciated.

For purposes of testing you could add a threshold layer instead of making the modification directly to the image.

Maybe you could post a link to one of the images so we can take a look at what you’re up against.

Good luck,
Ron

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