Apache OpenOffice (AOO) Bugzilla – Full Text Issue Listing |
Summary: | Export to grayscaled jpeg uses 24 Bit instead of 8 Bit | ||
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Product: | Draw | Reporter: | Regina Henschel <rb.henschel> |
Component: | save-export | Assignee: | wolframgarten |
Status: | CLOSED FIXED | QA Contact: | issues@graphics <issues> |
Severity: | Trivial | ||
Priority: | P4 | CC: | ace_dent, issues |
Version: | OOo 2.4 RC6 | Keywords: | oooqa |
Target Milestone: | OOo 3.3 | ||
Hardware: | All | ||
OS: | Windows XP | ||
Issue Type: | DEFECT | Latest Confirmation in: | --- |
Developer Difficulty: | --- |
Description
Regina Henschel
2008-03-25 13:18:28 UTC
Confirmed with OOo 2.3.1 WinXP PC. Greyscale export saved as 24bpp rather than 8bpp. Can confirm this with OOo 2.4-dev on Win2k. OOo Draw seems to export the jpg-image as RGB/YCbCr triplets, instead of saving just the luminance component (Y). 1.) The space savings from getting rid of the near-empty chroma channels (Cb and Cr) won't be large; but the decoding time for a grayscale JPEG is substantially less than that for a color JPEG. 2.) The bigger problem stems from the fact that the resulting "grayscale" image is actually a 24-bit RGB image, so editing it in another application results in RGB-editing. This may not pose a serious problem if one draws a red line on the image, as the user will notice that something went wrong, but it may be a problem when applying filters and various transforms. TRUE colours may be produced in this latter situation, yet the unsuspecting user may easily miss this fact. As the 2 chroma components are 0 (Cb = Cr = 0) in a grayscale image, the luminance (Y) is basically identical with the R/G/B values (when scaled to 255; Y = R = G = B). This should be relatively easy to fix. [The chroma components are scaled to 255 for true 24-bit RGB images, so they would become 128 rather than 0.] I can reproduce the bug in dev300m3. keyword: performance This issue has been fixed in cws[impress181] for OOo 3.3 sj->wg: this issue is ready to be verified in cws[impress181] Verified in CWS. |