Convert a photograph into an architectural blueprint. The filter finds the structural outlines in an image and renders them over a classic cyanotype-blue drafting grid.
The edge detection mechanism
The effect relies on a Sobel filter, a mathematical operation used in image processing to find areas of high contrast. It calculates the brightness gradient of every pixel compared to its neighbors. Where the contrast changes rapidly—such as the edge of a building or a sharp shadow—the filter draws a bright line. Areas with flat color or slow gradients are ignored, leaving the blueprint background visible.
Controlling the schematic look
Adjust the edge intensity to control how many lines appear in the final blueprint. A higher intensity forces the filter to trace subtle textures and faint shadows. A lower intensity restricts the filter to only the sharpest, most obvious borders, producing a cleaner architectural schematic.
The blue hue slider shifts the background color from a deep, saturated navy to a lighter, faded cyan. The drafting grid overlay can be adjusted to mimic paper scales, or removed entirely for a solid background.