Emboss a PNG

3×3 convolution · adjustable depth · grey or colour · batch

Emboss turns an image into what looks like grey relief stamped into metal or stone. It's a classic filter with a specific, narrow use — logos, textures and type where you want a carved impression rather than a picture.

How the relief appears

The filter is a 3×3 convolution with an asymmetric kernel: negative weights along the top-left diagonal, positive along the bottom-right, and a mid-grey offset added so the result sits around 128 instead of clipping to black. Areas where the image is flat come out uniformly grey; edges come out light on one side and dark on the other, which the eye reads as a raised or sunken surface lit from the upper left.

Because the effect is entirely edge-driven, images with lots of fine detail turn into grey noise while bold shapes emboss cleanly. Depth scales the kernel — around 1 gives a subtle impression, 3 and above gives hard metallic relief with visible clipping on strong edges.

Grey versus colour

Grey output is the traditional emboss, and usually the better-looking one: it reads as a single material. Unticking it keeps each channel's relief separately, which produces coloured fringing along the edges — an iridescent, slightly psychedelic result that can be useful as a texture but rarely reads as "embossed".

Nearby effects: Edge detect extracts the same edge information as lines on black, Sharpen uses a related convolution to enhance rather than replace, and Gradient map will tint a grey emboss into bronze or stone tones convincingly.

FAQ