I have noticed, that some people write a temporary file to loda a image. To help this people I have write a small program, that converts a image to code. I know, you can just use textutils.serialize but the output of my program looks better,

Instalation:
wget https://raw.githubusercontent.com/Wilma456/Computercraft/master/Tools/imagecon.lua imagecon.lua
Or with Packman

Usage:
imagecon <inputfile> <outputfile>
inputfile is the path of your Picture.
After Running you can copy the content of the outputfile in your program.

ExampleThe Picture

b	 b	b b b   b	b	b	  b  bbb bbbb
b   b b  b  b b   bb  bb   b b	bb  b   b
  b b  b b   b b   b bb b  bbbbb  bbbb bbb bbbb
   b	b	b bbb b b  b b	 b   b  bbb bbbb
is converted into

local tImage = {
{02048,00000,00000,00000,00000,00000,02048,00000,00000,00000,00000,02048,00000,02048,00000,02048,00000,00000,00000,02048,00000,00000,00000,00000,02048,00000,00000,00000,00000,02048,00000,00000,00000,00000,00000,00000,02048,00000,00000,02048,02048,02048,00000,02048,02048,02048,02048},
{00000,02048,00000,00000,00000,02048,00000,02048,00000,00000,02048,00000,00000,02048,00000,02048,00000,00000,00000,02048,02048,00000,00000,02048,02048,00000,00000,00000,02048,00000,02048,00000,00000,00000,00000,02048,02048,00000,00000,02048,00000,00000,00000,02048,00000,00000,00000},
{00000,00000,02048,00000,02048,00000,00000,02048,00000,02048,00000,00000,00000,02048,00000,02048,00000,00000,00000,02048,00000,02048,02048,00000,02048,00000,00000,02048,02048,02048,02048,02048,00000,00000,02048,02048,02048,02048,00000,02048,02048,02048,00000,02048,02048,02048,02048},
{00000,00000,00000,02048,00000,00000,00000,00000,02048,00000,00000,00000,00000,02048,00000,02048,02048,02048,00000,02048,00000,02048,00000,00000,02048,00000,02048,00000,00000,00000,00000,00000,02048,00000,00000,00000,02048,00000,00000,02048,02048,02048,00000,02048,02048,02048,02048},
}

paintutils.drawImage(tImage,1,1)