Pixelate Image
Drop in a picture, drag a box over the part you want blocked out, set the block size and download it. The blocks are drawn over the selection only: every pixel outside the box is copied into the new file byte for byte, so this covers one face or one label and leaves the rest of the photograph exactly as it was. Inside the box, each block becomes the mean of the red, green and blue of the pixels under it, rounded to the nearest whole value because a channel is a whole number, and every pixel keeps its own alpha, so a transparent area stays transparent in a PNG. A block that hangs off the edge of the selection averages only the pixels that exist rather than pretending to be a full square, and the page prints how many blocks there are and how wide the last column is. The picture is decoded, averaged and written inside this tab: nothing is uploaded, there is no account, and no file size limit is imposed.
The picture appears here.
· or drop one anywhere on the stage
Drag a box over the part you want blocked out, or switch to the whole image. Tab to the box and the arrow keys move it, shift with an arrow resizes it, and the four fields set it exactly. Blocks run from 1 to 256 pixels.
Common questions
- How do I pixelate only one part of an image?
- Choose a picture and a box appears over the middle of it. Drag a new box on any part of the picture outside the current one, drag the box itself to move it, or type the four numbers under the readout: left, top, width and height, in the picture's own pixels. Only the pixels inside that box are averaged into blocks. Everything outside it is copied into the file you download without a single byte changing, so a portrait keeps its background exactly as it was and only the face you covered is blocked out. If you do want the whole picture pixelated, the Apply to row switches from Selection to Whole image.
- What block size should I use?
- The block size is the width in pixels of one square of flat colour, and it can be any whole number from 1 to 256. A block of 1 is a single pixel, whose average is itself, so the picture comes back unchanged: that is the honest answer rather than an error. Somewhere between 10 and 30 is usually right for a face in a phone photograph, and a large picture needs a larger block than a small one to hide the same amount of detail, because the block is measured in the picture's own pixels and not in the pixels of the preview on screen. The page prints how the grid falls, for example 6 × 4 blocks of 25 px, so you can see what you are asking for before you download it.
- Can pixelation be reversed, and is it safe for hiding private details?
- Treat it as a visual effect, not as a security control. The detail inside a block really is replaced in the file you download, so there is no hidden layer to peel off, but that is not the same as being safe: a small block over regular shapes such as printed digits leaves a pattern that a person or a program can often match back to the original characters. There are published attacks that recover pixelated text by rendering candidate strings and matching them against the blocks. If what you are covering must stay secret, such as a password, an account number or an address, paint a solid shape over it in an image editor instead, so the pixels that come out carry nothing from the pixels that went in.
- Does transparency survive?
- In PNG, yes. Each pixel keeps its own alpha value: only the red, green and blue channels are averaged, so a transparent corner comes out transparent and a soft edge keeps its softness. JPEG has no transparency at all, so when you choose JPEG the picture is composited over white before the file is written, and a transparent area comes out white rather than whatever the browser would otherwise have put behind it. The Transparent areas row under the tool says which of those two you are about to get.
- Should I download a PNG or a JPEG?
- PNG for anything you plan to edit further, for a picture with transparency, and for screenshots of text: it stores every pixel exactly, so the flat blocks stay flat. JPEG for a photograph you want to be smaller, where the file is written at high quality. Either way the download is the full picture at its original pixel size with only the selected area changed, named after your file with the block size in it, so a 25 pixel job on photo.jpg arrives as photo-pixelated-25px.png.
- Is my picture uploaded anywhere?
- No. There is no server in this. The file is read in the page, decoded by the browser's own image decoder, averaged into blocks by code running in this tab and handed back to you as a download. No image byte is sent to an endpoint, to analytics or to error reporting. The only thing written to your browser's storage is the setting row: the block size and the output format you last used. No picture is ever stored, and if storage is blocked the tool still works.
- Is there a limit on the size of the picture?
- None is imposed. Nothing is uploaded, so the bytes on disk are nobody's business, and there is no megapixel cap on what you can open. The practical ceiling is your own machine: a picture too large for the browser to hold in memory is refused in plain words, naming its size and suggesting a smaller copy, rather than handing you a blank file. Your original file on disk is only ever read, never altered.
- Can I use it without a mouse?
- Yes. Tab to the box drawn over the picture and the arrow keys move it, with shift and an arrow resizing it; each press moves one screen pixel, or one source pixel when that is the larger, so a big photograph previewed small still moves at a useful rate. The four number fields under the readout set the selection exactly, and the block size, the Selection or Whole image choice and the format are all ordinary labelled controls. The picture, the selection and the block grid are also described in words on the page, so a screen reader gets the same facts the canvas shows.
Each block becomes the exact average of the pixels under it, and everything outside your selection is copied unchanged. Pixelating is a visual effect, not a security control: a small block size over regular text can leave the shape readable, so do not rely on it to hide a password or an account number.