Use this field to specify meta-information required by the explicit image formats: `gradient`, `plasma`, `label`, and `caption`. For `gradient` or `plasma` specify a color range such as `blue-yellow`. You can also specify `fractal` for the `plasma` image format. For `label` specify any text to render as a label. The `caption` format is similar except you can enter a paragraph rather than a single line of text. Finally, for `hald` specify the number of levels, typically 8.

Choose a format of `xc`, set the canvas size, and set this field to the canvas color. Choose `none` to create a transparent image.