SDL2_Image port, having problems with .png images

[HudsonSchumaker]

Hello,
I having problems with .png images, the colors rendered in the screen are differ from original file.
the least bad pixel format i found is SDL_PIXELFORMAT_RGB565

original image:

rendered:

code: https://github.com/HudsonSchumaker/ps2-demo-c/blob/8aa4f323b008bb12c69c45aaf71168b4be19eec3/src/de-ps2/io/loader.c#L27

so in summary how to do it properly ?

thanks in advance

[YCistak]

The problem is the SDL_ConvertSurfaceFormat(surface, SDL_PIXELFORMAT_RGB565, 0) step. The PS2 renderer only supports two texture formats — see SDL_render_ps2.c:

.texture_formats = { SDL_PIXELFORMAT_ABGR1555, SDL_PIXELFORMAT_ABGR8888 }

so when you hand it an RGB565 surface, SDL_CreateTextureFromSurface has to convert again to the nearest supported format, and 565→1555 goes through a lossy path (and you throw away alpha in the process). Convert straight to what the GS actually uses:

SDL_Surface* ps2_surface = SDL_ConvertSurfaceFormat(surface, SDL_PIXELFORMAT_ABGR8888, 0);
// or SDL_PIXELFORMAT_ABGR1555 if you want 16-bit textures to save VRAM
SDL_Texture* tex = SDL_CreateTextureFromSurface(ctx_get_renderer(), ps2_surface);

Even simpler: skip the manual conversion entirely and pass the IMG_Load surface directly to SDL_CreateTextureFromSurface — it picks the best supported format itself. Use 1555 only for images without gradients (it's 5 bits per channel), 8888 for everything else.