I would like to enlarge images for use as desktop backgrounds but find I must make the ones I want less grainy. They are initially much smaller and must be scaled. I am told that Adobe Photoshop can fix this through a process called "dithering" but that it is expensive--about $1000. I am looking for free software that can do the same. I like GIMP but do not know if it can dither.
Unless you're working with svg files, scaling usually ends up in lower quality pictures.
Whenever I have to add a default wallpaper to a windows image, which happens when the customer wishes to add corporate branding to every workstation, I usually ask for high res pictures usually in the 2300x1900(ish) resolution range.
This takes care of 2 things, 1) the wallpaper will have good quality, and 2) the customer is aware that a lower res picture will have poor quality on high res screen ( I make sure that they are well aware when I tell them what the minimum requirement is, in the end I'm not a designer but a sys admin / devop
If you can, ask for a high res picture or svg file, the latter can be resized without loss
Agree with Marcuzzo, any resize to a bigger width/height will degrade your picture. Always, even if you use photoshop which gives a very nice resize with bicubic option.
- Don't attempt to resize from low quality JPG, it does not work. Use PNG or BMP as a base.
- When I resize a photograph I always choose a prime number percentage, such as 177% (max)
- Instead of full screen wallpaper, you could choose to center a smaller picture on the screen and adjust the surrounding desktop color to black, or the color of your picture.. It looks quite nice.. and it is also easier to see your program icons on the desktop.