Color conversion aid on a website

As part of my first Magento-shop, I want to offer visitors the possibility to upload photos that the software converts to embroidery/needlepoint designs The software I need does pretty much what I've seen on a Dutch websites [login to view URL], [login to view URL] [login to view URL] or [login to view URL] It offers the choice for fabrics varying in density, resulting in coarse or fine designs It offers the visitor to limit the photo's dimensions, either by entering width or by height. These values represent horizontal and vertical stitches in the design. It offers the visitor to choose a base colorset (e.g. yarn brands like DMC or Anchor). The number of of available colors in every single set can be up to 600-800 colors. Every color in every set refers to a name and a symbol (both manageable by me in tables). RGB or hex values of every color, names will be supplied by me prior to the software design. The symbols are It offers the visitor to choose between color, greys and sepia color subsets. It offers the visitor to limit the number of colors in the set. This effectively results in less complex embroidery designs and less required yarn, making it cheaper. The color conversion works pretty much like Photoshop indexing colors capabilities. Photoshop uses a maximum of 256 different colors. This is sufficient for me, too. If the result is satisfactory to the visitor, its settings need to be stored in his/her shopping cart, enabling me to send the pattern (using the symbols) and the requested yarns.