January 23, 2026
We often throw around terms like CPU, GPU, or VRAM. Here, we explain in simple and understandable terms what these components do for darktable.
CPU (processor) – The construction manager
The CPU is the brain of your computer. It is extremely smart and can solve very complex tasks, but it usually processes things one after the other.
- In darktable: It handles administration, image loading, and modules that cannot (yet) run on the graphics card.
GPU (graphics card) – The worker column
The GPU may not be as “smart” as the construction manager, but it has thousands of little workers. It is perfectly suited to changing millions of pixels at once (e.g., making all pixels brighter).
- In darktable: It’s the turbo. When OpenCL is active, it does the heavy lifting during editing and exporting much faster than the CPU.
RAM (random access memory) – The desk
This is where all the data that the computer needs right now is stored. The larger the desktop, the more files (images) can be open at the same time without having to laboriously retrieve them from the archive (hard drive).
VRAM (video memory) – The material cart
This is the ultra-fast memory that is built directly onto the graphics card. It is like a material trolley standing right next to the work crew (GPU).
- Why is this important? If your image fits completely into the VRAM, the GPU can process it at lightning speed. If the VRAM is too small (e.g., for huge 61-megapixel images on old cards), the data has to be constantly moved back and forth, which slows things down.
OpenCL – The language of workers
OpenCL is not hardware, but rather the “language” that darktable uses to give commands to the graphics card. Without functioning OpenCL, the graphics card does not understand what it is supposed to do, and the CPU has to do all the work on its own.