I'm trying to make a comp that is 1px wide for a slit scan type effect but the minimum seems to be 4px? I've never run into this before is this a known limitation?
You can't render any compressed movie that has only one pixel row or column. Color compression requires 4 pixels.
What are you trying to create? You can draw a 1-pixel-thick line, and the color may be pretty close if the line is precisely aligned on the pixel grid. However, if it is off by 1/4 of a pixel or at any angle, the color and luminance of the line will change.
Please let us know what you are trying to create and animate, and we'll provide some suggestions. When I request vector artwork or create my own, I always specify that all horizontal and vertical edges of the design are precisely aligned on the pixel grid and that no line is less than 2 pixels wide.
1 x 1080 size comp with footage, layered back on top of the original shot.
CC RepeTile used to repeat that pixel and stretch the edge of the image like so, ideally this would be a 1px stretch, but its repeating 4px each time.
Then an adjustment layer and a gradient shape to drive time displacement from the middle to the right edge
It works for the most part but ideally its just a 1px slit not a 4px slit. Obviosuly temporal aliasing is more of the issue here not the width of my middle pixel, but still if I had high enough frame rate footage or the motion was slow enough I would want the smoothest result possible. This is just a test with some stock footage for a potential job.
Again the workaround seems to be to crop your 4px by 1080 comp with the region of interest tool to get 1px, but seems like an artificial limitation of the comp dialog box since the program can handle it and doesn't seem to cause any errors.