Dithered GIFs and non-Dithered GIFs

Here I will compare and contrast dithered and non dithered GIFs in terms of quality and file size. Dithering is the process of interpolating the missing colours within a GIF based on the colours around the blank spot. This process will allow one to lessen the amount of colours within a GIF from say 256 to 128 and not have black or white spots noticeable. This will help with file storage also. But just how helpful is this process?

Above we have a graph of GIFs that have not been dithered and colours being added from 2 to 256 going horizontally and the file size along the y-axis. Take the data for the grave image, at 2 colours it takes up a lowly 13.5 kb of space, this is nothing for almost any storage device which is fantastic, however if we look at the image quality below;

This is clearly a horrible picture and not a very good representation of the original image below;

Clearly they are very different between the first and second image 254 colours have been added to create the actual image. Although the file size for the full image may be 241 kb, the quality is obviously ideal. Now if we look at how the dithered files data is displayed;

It immediately becomes apparent that when a GIF is dithered the file is larger, possibly due to the interpolated pixels. As the grave picture without dither was 13.5 kb when only 2 colours were displayed and with dither the same image is 19.5 kb. Here is the grave photo with 2 colours while being dithered;

We can see that this is much clearer than it's non-dithered counterpart, as the headstones appear more grey and every object is easily identifiable as opposed to the non-dithered photo. This is becasue the missing colours are being interpolated based on the surrounding colours, hence the grey where the headstones are, the green where the grass is and the black for the shadow.

Here is the image, dithered with 16 total colours and is 87.4 kb, I personally believe that this is the best quality to size ratio to use, and I believe that a dithered image is also the best choice as it appears more whole and less choppy than its none dithered counterpart.