Load custom images into Minecraft.
You can load any image doesn't matter the size (within reason), however, it should be kept in mind that all blocks are 128x128 pixels. So, if your image is massive then it may take a lot of blocks to display and may also lag the client.
On that note, images are rendered better if they are in increments of 128 pixels, but it doesn't make too much of a difference since it is resized in the background to fit regardless. These images below are examples of random images that I loaded into the game to be displayed.
Any image format that Java can support is also supported. However, types other than PNG or JPG/JPEG may not be displayed in the list command.
To add an image without clicking a block, hold an item in your hand when creating the image and right click anywhere in the air; the image will be placed in front of you.