![]() One of the many features of GIMP is the ability to create gradients. Here you find other Tutorials about embedded GUI.GIMP is a powerful open-source image editing software that allows users to create and edit images with ease. Now you know how to improve the quality of your 16-bit images using dithering. Then you need to copy the result C file to you project and use it with an Image obejct. Just upload it to the Online Image Converter tool which creates a C array from a BMP, JPG or PNG image. Once you have a dithered image you can use it LittlevGL as other images. Here is an example to see the difference between the original, non-dithered and dithered images: It is useful if you have a high DPI monochrome display. You can use GIMP to create black and white dithered image too by selecting Image->Mode->Indexed and Use black and white color palette as Colormap and Floyed-Steinber as Color Dithering. To use it, in a terminal type: convert image_in.jpg -ordered-dither o8x8,32,64,32 image_out.jpg How to dither an image to 1 bit (black and white)? It knows a lot of algorithms manipulates you image. is very complex and versatile a command line tool. To make dithering open GIMP and click Image->Mode->Dither to RGB565 and save the new image. gpl) file to the palette directory of GIMP (On Linux: /home/user/.gimp-/palettes) Copy the the 4 Grayscale palette files (.Copy the dither16bit.scm file to the script directory of GIMP (On Linux: /home/user/.gimp-*/scripts). ![]() If because of any reason the link above become broken you can also download the plugin from here. I just followed the steps in the description to add the plugin to GIMP. GIMP needs a plugin to make this kind of dithering. GIMP is a free and cross platform software to manipulate images. The most simple way to dither your high color depth image to 16 bit is using a photo editor software. How to dither your 24 bit images in RGB565 format? The enlarged dithered image looks a little bit noisy. However if you look it carefully you can also notice a few stripes but it is much better then the non-dithered version. The dithered image with also 16 bit color depth looks almost the same like the original. The stripes are clearly visible on the enlarged image too. If we convert image to 16 bit color depth ugly stripes appear because this color depth can’t show enough colors. Original enlargedĮven if we are looking an enlarged part it seems perfect. The original image with 24 bit color depth has got smooth color gradients. To learn more about the dithering algorithms I suggest this article: Image Dithering: Eleven Algorithms and Source Code Original 24 bit (RGB888) image It sounds simple but real algorithms are counting the error after putting pixels and apply a different “tricks” to avoid artifacts. To make the color lighter use more white pixel, and to make it darker use more black pixels. On average it will result from a gray color. It’s simple just put a black pixel and a white after it. To understand dithering firstly figure out how to create a gray color from only black and white. All this can be done in compile time without performance loss. If you use a dithered image you will get a much better result on lower color depth. The exception is the subtle color fades where simply there is not enough color to create a smooth fade. On embedded systems 16-bit color depth is very common because it needs much less “wire” and memory than 24-bit colors and usually there is no or only minor difference in quality. Working form the same color palette (same number of colors) the dithered image looks much better.Ĩ bit (256 colors) image without ditheringĨ bit (256 colors) image with dithering Why use dithering? Both of the images below are using only 256 colors but the right one is dithered. It gives the effect that your image has greater color depth by manipulating pixels by a smart algorithm. ![]() What is dithering?ĭithering is an image (and audio) processing method. In this post, I will show you how to apply dithering on higher color depth images to get a better result at 16-bit color depth. Fortunately, there is a solution which is called dithering. The 65k colors might be not enough to show the similar colors properly, but ugly stripes will appear. I’m sure that you have already faced with the problem when you have only 16-bit color depth and an image with smooth color fades.
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