Image Tools
These image tools resize, convert, inspect and edit pictures in your browser. All 12 work on a canvas in the page, so the file is never uploaded and never leaves your machine.
12 tools
- Collage MakerThe collage maker combines up to 24 images into a grid, with control over the column count, the gap, the cell size and whether a picture is cropped or fitted.
- Color PickerA color picker that reads the exact pixel you click in any image, giving its value in hex, RGB and HSL, with a magnifier so you can land on the right pixel.
- Grayscale ConverterConvert an image to grayscale using three different channel weightings, with an adjustable strength slider so you can stop part-way for a desaturated look.
- Image Color ExtractorThe image color extractor pulls a dominant palette out of a picture using median cut quantisation, and reports the share of the image each colour accounts for.
- Image CompressorThe image compressor shrinks a file with an adjustable quality setting and an optional width cap, showing the before and after sizes as you move the slider.
- Image Flipper and RotatorThe image flipper and rotator turns a picture by right angles and mirrors it on either axis, with no quality loss, because every operation is lossless.
- Image ResizerResize an image by pixels or percentage, stepping down in halves so the result stays sharp.
- Initials Avatar MakerThe initials avatar maker generates a clean PNG from one or two letters, in four sizes and three shapes, with the colour derived from the initials themselves.
- Invert ColorsInvert colors in an image to produce a photographic negative, flipping every channel to its opposite. The operation is its own inverse, so it undoes itself.
- Monitor Calibration TestMonitor calibration test patterns for black level, white level, greyscale, colour, gamma and uniformity, with what to look for spelled out under each one.
- Pixelate ImagePixelate an image by replacing square blocks with the average colour inside them, with an adjustable block size, and a caveat about using it to hide anything.
- Sharpen ImageSharpen an image with an adjustable unsharp kernel, with the actual matrix shown.
What the image tools cover
The 12 tools cover four jobs. Resizing and compressing change the pixel dimensions or the encoded quality. Converting moves between PNG, JPEG and WebP. Inspecting reads colours out of an image, either one pixel at a time or as a dominant palette. Editing applies a specific, reversible operation such as a rotation, a flip, an inversion, a sharpen or a pixelation.
Resizing and compressing are different operations that both make a file smaller, and confusing them is the most common mistake here. Resizing changes how many pixels there are. Compressing keeps the pixel count and re-encodes them at lower fidelity. Doing both, in that order, gives the smallest file for a given appearance.
Large reductions are done in stages rather than one jump, because a single large downscale drops detail the browser would otherwise keep. Rotation by a right angle and flipping are lossless, since each is a rearrangement of existing pixels rather than a re-encode.
Resize, compress or convert
These three overlap in outcome and differ in what they change.
| What you want | The tool |
|---|---|
| Fewer pixels, for a fixed display size | Image resizer, by exact dimensions or by percentage |
| A smaller file at the same dimensions | Image compressor, with the before and after sizes shown as you move the slider |
| A different format | Image converter for PNG, JPEG and WebP, or image to WebP for that one target |
| The exact colour of one pixel | Color picker, with a magnifier so you land on the right pixel |
| The main colours across a whole picture | Image color extractor, which reports the share each colour accounts for |
| To obscure something in a picture | Pixelate image, with the caveat that pixelation is not secure redaction |
Frequently asked questions
Are my images uploaded when I use these tools?
No. Each tool draws the image onto a canvas element inside the page and reads the pixels back from there. No request carries the file, and the site has no backend to receive one. The image is discarded when you close the tab.
Should I resize or compress to make a file smaller?
Resize first, then compress. Resizing to the size the image will actually display removes pixels nobody sees, and compressing afterwards works on a smaller starting point. Compressing a large image without resizing it keeps every pixel and degrades all of them.
Does pixelating a picture safely hide the information in it?
No. Pixelation averages blocks of pixels and is reversible in some cases, particularly for text and for anything drawn from a small set of possibilities. To remove information, crop it out or cover it with a solid shape and export a new file.
Why did my transparent PNG gain a white background?
Because you converted it to JPEG, which has no alpha channel. Transparent pixels must become a solid colour, and the converters fill with white unless you choose another colour. Converting the result back to PNG restores the channel but not the original pixels.