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jpg memory allocation - bugreport 555033

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jpg memory allocation - bugreport 555033 fremobit 05 Oct 00:29
  jpg memory allocation - bugreport 555033 Daniel Hornung 05 Oct 01:16
  jpg memory allocation - bugreport 555033 Sven Neumann 05 Oct 01:44
fremobit
2008-10-05 00:29:17 UTC (about 16 years ago)

jpg memory allocation - bugreport 555033

for the interrested http://bugzilla.gnome.org/show_bug.cgi?id=555033

As stated by Sven Neumann that a bug report on this issue might be the wrong attemption to clear this issue I'll try my luck with this list. As written in the bug report, 555033, gimp tries to allocate more memory than it mathematically needs to.
In my opinion the needed memory for an image of the dimensions 15000px to 15000px at 8bit depth is 214,57MB but Gimp allocates 1,1 GB.

Any Suggestions ?

Thanks in advance. Uwe Liebrenz

Daniel Hornung
2008-10-05 01:16:00 UTC (about 16 years ago)

jpg memory allocation - bugreport 555033

On Sunday 05 October 2008, fremobit wrote:

In my opinion the needed memory for an image of the dimensions 15000px to 15000px at 8bit depth is 214,57MB but Gimp allocates 1,1 GB.

This is an old discussion, but your case seems simpler than the usual discussion/guesses: 8 bit means 8 bit per channel (RGB, and in some cases also alpha)

215MB sound as if you did calculations for an image with only one channel, such as a grayscale image.

Sven Neumann
2008-10-05 01:44:15 UTC (about 16 years ago)

jpg memory allocation - bugreport 555033

Hi,

On Sun, 2008-10-05 at 00:29 +0200, fremobit wrote:

In my opinion the needed memory for an image of the dimensions 15000px to 15000px at 8bit depth is 214,57MB but Gimp allocates 1,1 GB.

GIMP is not an image viewer, it is an image editor. As such it needs to allocate not only the memory to hold the image data. It also needs to hold the image's selection mask and the image projection plus a number of scaled down versions of that projection. The latter are needed for accurate and efficient display of the zoomed out image. Depending on the image type, this easily sums up to more then 10 bytes per pixel for a single-layered image.

For a grayscale image, as in your example, the factor is about 4.666 (1 byte layer data, 1 byte selection mask, 2 bytes for the grayscale-alpha projection multiplied by 1.333 to account for the tile pyramid).

Sven