Every colorwork sweater, hat or blanket starts with a chart, and graphing your own picture square by square takes ages — whether it's your dog's face, a team logo, a name or a motif. This generator charts any picture for free, right in your browser.
For knitting, set the width in stitches and your gauge: stitches and rows per 4 in (10 cm). Knit stitches are wider than they are tall, so a chart drawn on square cells comes out squashed; the generator works out the number of rows so the picture keeps its proportions, and shows the approximate finished size. Choose 2 to 8 colors — two to four is typical for stranded colorwork.
For crochet there are two modes on a square grid: tapestry crochet and C2C (corner to corner). For C2C the PDF adds a written pattern for every diagonal row — which way to work it and how many tiles of each color, like "3 A, 2 B".
On the chart the main color is left blank and the others get symbols; rows are numbered from the bottom and stitches from right to left, the way charts are read while knitting. The PDF comes on US Letter or A4 with a key and a stitch count for every color. Simple pictures with bold shapes and strong contrast chart best.