An image guide file is a text file containing one or more drawing commands which describe guides to overlay on compositing images.
In a compositing viewer pane, open the right side toolbar and click Display Options or press D to open the Display Options window.
Click the Viewport tab.
Use the Image Guide option to set the image guide file to use.
All coordinates are expressed in pixels.
color R G B A
Sets the drawing color.
box X Y Width Height
Draws a box at (X,Y) with the specified Width and Height.
rect X1 Y1 X2 Y2
Draws a box with one corner at (X1, Y1) and the opposite corner at (X2, Y2).
line X1 Y1 X2 Y2
Draws a line from (X1, Y1) to (X2, Y2).
lines N dX dY X1 Y1 X2 Y2
Draws N lines from (X1, Y1) to (X2, Y2), offsetting both coordinate pairs by ( dX, dY) each time. Use this to draw grids.