vischeck.com

Tool Positioning

Vischeck is a long-standing online tool launched back in 2000. Its core function is to let users with normal vision simulate how people with color blindness see the world, while offering image correction via the Daltonize algorithm to make color information that is hard for color-blind people to distinguish perceptible. It also comes with an extra feature called TinyEyes that simulates infant visual development. Built on algorithms from authoritative academic research, it still works stably to this day.

Core Features & Pricing

It has three core features: First, it uses the classic Brettel/Vienot/Mollon LMS projection algorithm to support simulating the visual experience of different types of dichromatic color blindness. Second, its Daltonize correction function shifts information originally in the red-green color dimension to brightness and blue-yellow dimensions, preserving information that color-blind users can perceive. Third, the TinyEyes feature simulates the visual effect of infants at different ages based on developmental vision research.
The tool is completely free for personal non-commercial use. All processing is done via client-side JavaScript, with no need to upload images. For commercial use, you need to contact the author for authorization, and you can pay for consulting and technical support. Its source code is open-source under the GPL license and hosted on Github.

Pros & Cons

On the plus side, Vischeck's algorithms come from authoritative research in the field, have been widely cited and verified in academia, and deliver far more accurate simulation results than most similar tools. It is completely free, ad-free, open-source for self-hosting, and client-side processing also protects users' image privacy. The disadvantages are obvious too: its interface is an old early design, there is no Chinese language support, the operation logic is fairly plain, it only supports processing one image at a time with no batch functionality, and there is no public standardized process for commercial licensing.

Suitable Use Cases & Accessibility

This tool is ideal for UI designers and front-end developers to verify the color accessibility of their product designs. It can also be used by color-blind users to correct images on their own, or for teaching demonstrations in the visual research field. Currently, users in China can access and use the website directly, no proxy required.