Teletect Mosaic

A mosaic builds an image from small flat tiles. "Adaptive" mosaics vary the tile size across the image. Teletect Mosaic decides each tile’s size from the brightness where the tile begins.

Threshold is the brightness gate. Only parts of the picture above it (or below it, with Gate set to Below) are turned into blocks. The rest of the picture passes through unchanged. The LCD shows the raw brightness value.

Min Size sets the smallest block. At 0% the smallest "blocks" are the individual source pixels, unchanged. Min Size and Max Size are the two ends of the size range; if you cross them over, they are swapped internally.

Aspect sets the block shape. The center is square. Between center and the ends it steps through seven exact width:height ratios: 1:8, 1:4, 1:2, 1:1, 2:1, 4:1 and 8:1. Fully left fixes blocks at their minimum width (tall vertical strips; with Min Size at 0, independent one-pixel columns). Fully right fixes them at their minimum height (wide horizontal bars; with Min Size at 0, single sampled rows).

Smoothing softens the brightness used to decide block sizes, along each line. Higher settings stop fine texture from producing ragged size changes. At 0 it is bypassed. It affects decisions only; it doesn’t blur the picture.

Max Size sets the largest block. At 100% a block can extend to the full frame width or the remaining frame height.

Scale narrows the brightness window that maps onto the size range. At 0 the whole brightness range maps from Min Size to Max Size. Turning Scale up compresses the transition into a smaller brightness window, so sizes snap between small and large over a narrower band of tones. Window (Switch 11) sets where that window is centered. Scale changes the slope of the mapping, not the maximum size.

Above processes areas brighter than Threshold; Below processes areas darker than it.

Poster drops the lowest four bits of block color, for flatter, posterized tiles. Off keeps full color precision.

Normal makes blocks larger in brighter areas. Inverted makes them larger in darker areas. This is separate from Gate: Size changes which tones get big blocks, Gate changes which tones are processed.

Average fills each block with the average color of the first row of the block (up to 256 pixels of it), for smooth, blended tiles. Sample fills each block with the color of its top-left pixel, for sharper, more contrasty changes between tiles.

Centers the Scale brightness window on Mid-grey or on the Threshold setting.

Mix blends the original and processed pictures, with exact dry and fully wet endpoints.

Mosaic works one line at a time without storing a whole frame. When a block starts, its size, shape, color and gate decision are fixed for the whole block, and the rows below simply continue it until it ends. Coarse blocks sit on a 16-pixel horizontal grid and can reach 1920 pixels wide; in a 1080p frame the square mode can reach 1072 × 1072. Sizes between one pixel and 16 pixels are not separate steps: the fine end of the range preserves the source pixels exactly. Small fragments left over at the bottom of the frame pass through unprocessed rather than becoming distorted rectangles.

In interlaced formats (NTSC, PAL, 1080i) each field is processed on its own. A paused interlaced image has different source rows in its two fields, so block colors on fine texture can alternate between fields and appear to flicker. Use a progressive source (for example 1080p) for the steadiest blocks.