Transparency Tools
Trims transparent borders, flattens alpha onto a chosen colour, or extracts the alpha channel as a mask.
Four things people need from an alpha channel and one place to do them: trim the empty margin, composite onto a colour before the file becomes a JPEG, pull the channel out as a greyscale mask, or fade the whole thing. The result panel then tells you whether what you have will survive a 1-bit alpha format.
Drop an image with transparency, or one with a uniform border
Trim, flatten, or pull the alpha channel out as a mask.
How to use it
Pick the operation
Trim, flatten, mask or fade. Each shows only its own controls, because they share nothing but the input.
For a trim, set the tolerance
A JPEG’s “white” is 251 in places, so a tolerance of zero finds no margin at all on a real photograph and the trim appears to do nothing.
For a flatten, pick the colour deliberately
Whatever the image will sit on. The composite happens in linear light, which is what stops a grey seam appearing along every soft edge.
Read the three percentages
Opaque, transparent and partial. The partial figure is the one that decides which formats you can use.
Common questions
What is a 1-bit alpha, and why does it matter?
A pixel is either fully visible or fully gone — GIF, and a palette PNG with a tRNS entry, work that way. If your image has partially transparent pixels, those formats turn every soft edge jagged, so keep 8-bit alpha: PNG-32 or WebP.
Why does flattening in linear light matter?
Compositing is a weighted average of two colours. sRGB code values are not proportional to light, so averaging them averages the wrong quantity — which shows up as a darker grey seam along every anti-aliased edge.
The mask came out inverted from what my other tool expects.
White-is-opaque is the compositing convention and the default here; several print workflows use the opposite. The polarity switch flips it.
Feed it from
Background Remover
Keys out a flat or single-colour background in OKLab and returns a transparent PNG, with a brush for fixing the edges.
Subject Cutout
Cuts a person or an object out of an ordinary photo with an on-device segmentation model, and returns a transparent PNG with a soft, decontaminated edge.
Signature Maker
Draw your signature with a mouse, finger or stylus and download it as a transparent PNG or SVG.
Signature Extractor
Turns a photo of a signature on paper into a clean transparent PNG, removing shadows and paper texture.
Next
These accept what this tool produces, so the result can go straight in.
Background Remover
Keys out a flat or single-colour background in OKLab and returns a transparent PNG, with a brush for fixing the edges.
Border & Padding
Adds a solid, gradient or rounded border and padding around an image, or pads it to a target ratio.
Image Cropper
Crops to a freeform or fixed-ratio region and can auto-trim uniform or transparent borders.
PNG Compressor
Quantises the palette and rewrites the deflate stream to shrink a PNG without changing its dimensions.
EXIF Remover
Strips camera, GPS and editing metadata from photos while leaving the pixels untouched.
Favicon Generator
Produces the whole favicon set — ICO, PNGs, Apple touch icon, web manifest — plus the HTML to paste.