Files
test/source/blender/imbuf
Aras Pranckevicius 877d9c596a VSE: Fix various "off by half a pixel" issues in image transform
Code inside `IMB_transform` (which is pretty much only used inside VSE
to do translation/rotation/scale of image or movie strips) was not
correctly doing mapping between pixel and texel spaces. This is similar
to e.g. GPU rasterization rules and has to do with whether some
coordinate refers to pixel/texel "corner" or "center" etc. It's a long
topic, but short summary would be:

- Coordinates refer to pixel/texel corner,
- Do sampling at pixel centers,
- Bilinear filter should use floor(x-0.5) and floor(x-0.5)+1 texels.

Also, there was a sign error introduced in Subsampling 3x3 filter, in
commit b3fd169259.

After making the PR, I found out that this seems to fix #90785, #112923
and possibly some others.

Long explanation with lots of images is in the PR.

Pull Request: https://projects.blender.org/blender/blender/pulls/116628
2024-01-08 16:51:35 +01:00
..
2023-12-21 19:16:11 +01:00
2023-12-14 15:10:30 +01:00

The following 4 steps to adding a new image format to blender, its
probably easiest to look at the png code for a clean clear example,
animation formats are a bit more complicated but very similar:

Step 1:
create a new file named after the format for example lets say we were
creating an openexr read/writer  use openexr.c
It should contain functions to match the following prototypes:

struct ImBuf *imb_loadopenexr(unsigned char *mem,int size,int flags);
/* Use one of the following depending on what's easier for your file format */
short imb_saveopenexr(struct ImBuf *ibuf, FILE myfile, int flags);
short imb_saveopenexr(struct ImBuf *ibuf, char *myfile, int flags);

/* Used to test if its the correct format
int IMB_is_openexr(void *buf);

Step 2:
Add your hooks to read and write the image format these go in
	writeimage.c and readimage.c  just look at how the others are done

Step 3:
Add in IS_openexr to blender/source/blender/imbuf/IMB_imbuf_types.h
Add in R_openexr to source/blender/makesdna/DNA_scene_types.h

Step 4:
Add your hooks to the gui.
source/blender/src/buttons_scene.c
source/blender/src/toets.c
source/blender/src/writeimage.c

Step 5:
edit the following files:
blender/source/blender/imbuf/intern/util.c
blender/source/blender/src/filesel.c
blender/source/blender/src/screendump.c
and add your extension so that your format gets recognized in the thumbnails.

Step 6:
Alter the build process:
For cmake you need to edit blender/source/blender/imbuf/CMakeLists.txt
and add in your additional files to source_files.
If you have any external library info you will also need to add that
to the various build processes.

Step 7:
Its also good to add your image format to:
makepicstring in blender/source/blender/blenkernel/intern/image.c