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KB 1720

OpenCL (GPU) Support in Capture One

Last updated: 12-06-2018

Problem

What does OpenCL do and how do I use it in Capture One?

Solution

Optimal speed through OpenCL/GPU 

OpenCL is an open standard defining how to interface and utilize many processing cores with graphics cards (GPU), multiprocessor CPUs and RAM. OpenCL is short for Open Compute Language. As of June 2013, four major companies have developed drivers for OpenCL: NVidia, AMD, Intel and Apple.

For Mac OS X these drivers are part of the Operating System, where the drivers have to be installed manually under Windows.
The driver itself performs runtime compilation dedicated to the graphics card in the machine at hand. Only relatively new GPU cards have enough "compute power" to be utilized effectively.

Open CL will dedicate memory to several actions in Capture One.
The following outlines the softwares demand;
• Preview Update with different settings, styles etc: RAM
• Sorting/Rating: CPU cores and SSD speed
• Fit Image to Screen: GPU cores
• Process time: GPU processing units and CPU's and RAM


How to enable - what to expect
 

In Capture One versions 10 and later, Hardware Acceleration is set to Auto by default. In 9.3 and earlier, hardware cceleration is disabled by default, and you have to turn the preferences to AUTO to start testing your hardware for compatibility
You can expect much faster processing of files and overall performance improvement with suggested hardware.



Windows driver requirements

• For AMD/ATI graphics: AMD Stream 2.2, Catalyst 12.10 or higher Download here pick: AMD Catalyst™ Accelerated Parallel Processing (APP) Technology Edition
• For Nvidia graphics: NVidia Display driver version 306.97 or higher Download here pick "download".

Limitation in functionality

Certain Capture One settings will bypass the use of OpenCL and use the normal processing pipeline. These currently include:
• Use of Spot Removal


In case of problems using OpenCL

  • Mac: Clear the ImageCore Cache by deleting the folder (then restart Capture One):
    • Hard Drive > Users > Shared > Capture One
  • Windows or Mac If problems still occur, set OpenCL to Never in the Capture One preferences. Then restart Capture One.


How to completely disable OpenCL, in case of a crash at startup 

• Windows: run the script DONOT_useopencl.reg and restart Capture One (the download also contains a restore script to re-enable OpenCL useopencl.reg)  Download here
• Mac: Run this script “ToggleOpenCL.app” - disable OpenCL and restart Capture One Download here

• Mac 10.11 UPDATE: Run this script instead “ToggleOpenCLMacOS10.11.app” - disable OpenCL and restart Capture One Download here


OpenCL hardware support for Capture One


Generally speaking, any GPU that supports OpenCL 1.2 or newer and has a minimum of 1GB of dedicated RAM will be utilised. However, for more intensive processes, such as processing large files and using local adjustments - we recommend having at least 2GB of RAM.

When it comes to high-DPI displays such as 4/5K iMacs, this differs slightly. For any high-resolution displays, we recommend a minimum of 4GB of dedicated RAM.

Which Graphics Card (GPU) should I buy?


We often get asked which graphics card makes Capture One perform the fastest. The truth is, newer and faster cards are constantly being released, so it's difficult to recommend one brand or GPU in particular.

The things to look out for when purchasing a new GPU or workstation, would be the number of Stream Processors (AMD) and the number of CUDA Cores (Nvidia). The higher the value, the more processors available and thus giving you a faster experience in Capture One.

How many GPUs can I use with Capture One?


Capture One supports up to four GPUs, but for optimum performance ensure that these are form the same manufacturer, i.e. AMD or Nvidia.