What is a pixel map?

A pixel map is a test image drawn at the exact pixel size of one screen or LED wall. Played full screen with no scaling, each pixel of the file lands on one pixel of the display. People also call it a pixelmap, a test card or a test pattern. The part that matters is the 1:1 size: a pattern at the wrong size only proves that something scaled it. Open Ratio.

Make a pixel map at 1920 × 1080

What it shows

• Scaling. Grid lines are one pixel wide. Soft or grey lines mean the image is not 1:1.
• Crop and offset. A border on the outermost pixels disappears on the side that is cut off, and the centre label shows whether the image is shifted.
• Aspect ratio. Circles are drawn round. Ovals mean the picture is stretched.
• LED panels. In LED wall mode the card draws each panel's border and number, so a swapped, missing or dead cabinet is obvious from the audience position.
• Safe areas. Dashed guides show where titles still fit once the display crops a few percent off the edge.

How to make one

1. Find the screen's real resolution. For a TV or projector that is the native panel size, such as 1920 × 1080. For an LED wall it is panels across times pixels per panel, which the LED wall calculator works out from metres or feet.
2. Open Ratio at that size. A link such as /?size=1920x1080 fills it in.
3. Download the PNG, or a short MP4 if you also want to see whether playback freezes.
4. Play it in the media server at the same width and height, with scale set to none. The 1920 × 1080 test card and projector test pattern pages list the checks for those two cases.

A small example

A wall of 12 by 6 cabinets, each 192 × 192 pixels, is 2304 × 1152. A 1920 × 1080 pixel map on that wall cannot line up with the cabinets: the server would have to scale it, and the panel borders on the card would fall in the middle of panels. The pixel map has to be 2304 × 1152, opened with this LED wall link.

Questions

Is a pixel map the same as a UV map?

No. A UV map says where a piece of content lands on a physical surface, in metres. A pixel map is the test image at the surface's resolution in pixels. Ratio's output raster can export both for the same project: the pixel map, and a UV layout when the surfaces have real sizes.

What resolution should the content be?

The same as the pixel map, or a larger canvas that the media server crops from. Content made at a smaller size will be scaled up on the screen, and fine type will look soft.

Does it work in Resolume, disguise and TouchDesigner?

Yes. The file is a PNG or an MP4. Any player that can show an image at a set pixel size can show it. Nothing about the card is tied to one media server.

Do I have to sign up?

No. The card is drawn in your browser and downloaded to your computer. An account is only for saving a list of screens to use on another machine.