Easy tool color change

Hello, i want to make a tool what convert black and white JPG files to any two colors. This tool must work the same way as another present in a website whose address is in the attached file ([login to view URL]); i'm not the owner of that website. On this website you can load any JPG image, usually in black and white, and change them with two colors of your choice. Afterwards it is possible to download the image file with the colors changed and the resolution and size remains the same as the image loaded previously. For example, if the loaded image has 300dpi, 2400x3000 pixel, is sRGB and have about 3Mb, after the color change it will be returned to the public with the same features and only the Megabytes will be changed slightly. The operation of color change must be the main issue, it must be quick and efficient, for this I have provided you with a reference website to know how it has to work, especially in terms of speed of execution. I provide images for the tests you will find in the "images for test" folder. In the zip file you will find the layout of how my new site should appear, you will find it in the "layout example" folder; it is only indicative to understand how to place the buttons and the window where the initial demo image and the ones loaded later are displayed. I have provided you with some elements that you find in the "layout elements" folder, including the information text on the use, which can be activated with the single switch button. Note: - to upload the image file you need to do the Login, with unique password to everyone, I do not care that users have their own account. After logging in with a password, the "select JPG" button will appear about in the same position. - Indexing and ranking on search engines is NOT required. For any questions I am available. Thanks, Alex