Chris,
On 2010-06-25 02:54, Chris Mohler wrote: > On Thu, Jun 24, 2010 at 6:16 AM, Philip Rhoades<p...@pricom.com.au> wrote: >> Confirmation of what is going on from the gurus would be appreciated! > > It was as I guessed - the scans are in grayscale mode but the contents > are essentially a 1-bit image. > > Open a scan, do image->mode->bitmap, choose 1-bit palette. Then > rotate and save - the file size will be comparable to the original. > > Your image has that fine dot pattern all over the place - that's what > (I think) is causing the huge size blowup when rotated. Open a scan, > zoom to 100% or greater and look at the character of those small dots. > If you rotate the image in grayscale mode, look at the dots again at > 100% or greater - they are now quite blurry. Where each dot was n > pixels of solid black, now each dot is something like n+5 pixels of > shades of gray, which makes the image harder to compress efficiently. > > On the file increase when just saving - see here: > $ identify TestScanningDoc.png > TestScanningDoc.png PNG 2552x3523 2552x3523+0+0 PseudoClass 2c 8-bit > 230.383kb 0.740u 0:02 > > $ identify TestScanningDoc_nochange.png > TestScanningDoc_nochange.png PNG 2552x3523 2552x3523+0+0 PseudoClass > 256c 8-bit 366.076kb 0.870u 0:02 > > It appears the original has a 2-color palette, while the unchanged, > saved image has a 256-color palette. I resent my second mail (without the attachment) before reading your response - sorry about that . . Many thanks for the explanations - I appreciate it. Regards, Phil. -- Philip Rhoades GPO Box 3411 Sydney NSW 2001 Australia E-mail: p...@pricom.com.au _______________________________________________ Gimp-user mailing list Gimp-user@lists.XCF.Berkeley.EDU https://lists.XCF.Berkeley.EDU/mailman/listinfo/gimp-user
