[Digikam-devel] [Bug 307602] Large TIFF files crash digiKam (>1Gb)

[Marcel Wiesweg]

https://bugs.kde.org/show_bug.cgi?id=307602

--- Comment #37 from Marcel Wiesweg <marcel.wiesweg at gmx.de> ---
We are talking about in-memory compression, which means the uncompressed image
data is recompressed to save memory, but needs to be uncompressed each time the
image data is used (viewing, editing). That means the performance must be
suitable. Any sophisticated compression will be so slow that it cannot play a
role; LZO would be acceptable in speed, but obviously does not give any usable
benefit with our use case. Here comes ImageZero, which will give a benefit
regarding compression. 
The performance number given is 180MB/s for compression or decompression.
A 25 MPx image in 16 bit needs roughly these 180 MB of memory.
There are real-life situations where applying this compression to images in our
in-memory cache could give us a benefit, but there are as many situations to be
expected where we win nothing.
Regarding the problem of extremely large images: Axel's example here would need
30 seconds for compression, and another 30 seconds for decompression.

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