OSDev.org

Tosi wrote:What kind of bitmap do you want to use?
Windows bitmaps are actually pretty easy to use, especially since they are rarely compressed. The only problem is that due to the lack of compression they can be huge if they have big dimensions. There is also the problem of copyright, since it is a proprietary format. I don't use it often so I don't know the exact copyright or patent information.

According to Wikipedia (http://en.wikipedia.org/wiki/BMP_file_format):-

The simplicity of the BMP file format, and its widespread familiarity in Windows and elsewhere, as well as the fact that this format is relatively well documented and free of patents, makes it a very common format that image processing programs from many operating systems can read and write.

I don't know if that information is correct, and it doesn't mention copyright at all, but it looks as if it may be safe to use it. Recently I've been using bmp files to get photos into my OS where I can modify the colours and write the adjusted data back to the original files without modifying the headers (a 640x480 8:8:8 picture easily fits on a floppy disk), but it would be good to know if it's legal to generate bmp files directly from scratch. Does anyone know of anywhere you can go to find reliable information on which file formats you are allowed to use freely and which you cannot?

berkus wrote:Non-compressed BMP is free of patents. Using compression may be not.

It has nothing to do with copyright (entirely different thing).

IMHO just ignore patents and write code, if you go searching for patents you're violating.. you'll become depressed a web designer.

berkus wrote:Non-compressed BMP is free of patents. Using compression may be not.

Well, that suits my needs at the moment - I just need an easy way to get at photo data and compression only gets in the way of that. I'm now writing code to try to identify items in images, based at the moment on colour, textures and directionality of lines within different patches of similar pixels. In the future I'll obviously want to compress images, but I'll use jpg, and again Wikipedia suggests that the format's effectively free of patents, even if certain companies are unsuccessfully trying to claim it as theirs (see near the bottom of http://en.wikipedia.org/wiki/.jpg). I notice right at the bottom of that page that there's a public domain jpg compressor and decompressor available (C++ source file), so the way is open to putting this in your OS.

By the way, I've also got round the problem of widescreen not being supported by VESA on my netbook by stretching 640x480 images to 640x600 in an 800x600 screen mode, so circles now look like proper circles: four lines can be turned into five by using line one as the new line one, line four as the new line five, (line 2 + line 3) / 2 as the new line three, (line 1 + line 2 * 3) / 4 as the new line two, and (line 4 + line 3 * 3) / 4 as the new line four.

By definition, making a lot of money is volatilizing some patents; otherwise you should be safe from lawsuit. However I'm not a lawyer

bluemoon wrote:making a lot of money is volatilizing some patents; otherwise you should be safe from lawsuit.

Indeed. You go commercial and you get prosecuted for no apparent reason(?)