Re: [Openexr-devel] compression

[Piotr Stanczyk]

Hi Franco,

Hard to say without seeing more of the code/coontext, but if you wish to changes the compression schemes, then you will first have to load+uncompress the data into a intermediate buffer and then recompress with the new scheme of your liking.

Other attributes, chromaticities for example, imply how the data should be interpreted and as such do not require the above uncompress-compress cycle.



Piotr

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From: openexr-devel-bounces+address@hidden [openexr-devel-bounces+address@hidden on behalf of franco cortesi address@hidden
Sent: 07 February 2013 04:31
To: address@hidden
Subject: [Openexr-devel] compression

Hi!. i'm trying to change  compression types with exrstdattr. but it doesn't work:

//

// Load the input file, add the new attributes,

// and save the result in the output file.

//

InputFile in (inFileName);

Header header = in.header();

header.compression() = Imf::RLE_COMPRESSION;

it compiles but when i try to convert some files it raises:

 Quick pixel copy from image file ".." to image file ".." failed. The files use different compression methods.

dont know know exactly what i'm doing, just try and error. the purpose of this code is to use exrstdattr as back end for a little tool im working on, a command line and gui based batch exr conversor.

and sorry but i haven't found so much info about compression on exr docs or web searching :)