Contrast change not retained

i trying improve contrast of line art while contrast improves in preview when using curves or levels improved contrast not retained after clicking okay in curves or level adjustment. photoshop cs3, acrobat pro 8.

i have pdfs of scans of architectural drawings. open file in acrobat pro 8 , tiff. open tiff in photoshop, , convert bitmap grayscale.

i try improve contrast using levels or curves, while level or curve preview displays improved contrast (darker lines, more dots), when click okay apply change image reverts pre-adjustment contrast.

any suggestions?

thanks.

you trying adjust image bitmap. because made grayscale doesn't mean itself. bitmap has tonal values of 0 , 100 only. curve doesn't affect 2 tones (which in general want stay away modifying) won't anything. preview in ps, however, show change.

two ways make lines thicker you'd like. first, when converting grayscale, instead of 1 1 ratio, go 2 1 ratio, , you'll have grayscale image can adjust. way take image have that's not cooperating , blur small amount (say 0.5 1.5 pixels) , curves should hold.

either way, you're killing off pixel information , should resampling or blurring care. prefer blur method myself, have better incremental control of image (you can blur tenths of pixel). maybe can speak advantages of resampling?

j

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