Canvas size
How to Change the Canvas Size in Photasium
A caption, a border, or a square post often needs more room around a photo, and the photo should keep the pixels it already has. In Photasium that happens in the tab: the file never goes to a server.
Room around the picture
Canvas Size sets a new width and height on the document. The picture keeps its pixel size, and the anchor decides which edge or corner stays put while the working area grows or shrinks.
Image Size scales every layer to a new pixel count, so the same picture is smaller or larger. Crop sets a rectangle and drops what sits outside the working canvas. Canvas Size moves the working area around the pixels you already have.
Room for a caption
A story or a square post often wants the photo smaller than the frame, with a band for a name or a price. Raise the canvas and leave the centre anchor, and the extra space is split on opposite sides. Pick the top cell if the new space should sit under the photo for a line of type.
The photo stays the same number of pixels. Text can sit in the new band.
A listing can ask for a margin around the product, so the product stays off the edge of the frame. Canvas Size adds that margin, and the product stays the same number of pixels. Fill can paint the new area a flat colour. Image Size scales the product along with the table.
A window shot for a slide or a doc often sits tight against the edge. Add width and height, and pick a corner cell if the window should sit in that corner of a larger frame.
A print or a scan can need a wider page, or a border along one side. The anchor is the edge the existing picture stays on. A left cell keeps the photo on the left and puts the new paper on the right.
Changing the canvas in Photasium
Open a photo
Open the editor, then File → Open, or drop an image on the canvas.
Choose Canvas Size
Open Image → Canvas Size. The hint says this changes the working area without scaling pixels, and it shows the current width and height. Width and height start at that size. The centre cell of the anchor grid is selected.
Set the size
Enter width and height in pixels. The fields are separate, so changing one leaves the other as it is. Each side is kept between 1 and 8192 pixels, and a fraction rounds to a whole pixel.
Pick the anchor
The anchor is a grid of nine cells. The label is Anchor, and each cell’s tooltip says where the existing pixels stay. The centre splits added space on opposite sides: a wider canvas adds the same amount on the left and the right, and a taller canvas adds the same amount above and below. A corner keeps the picture in that corner, so the new area lands on the other two sides. An edge keeps the picture against that side, and the extra on that axis goes to the opposite side. The same cell is the part that stays inside when the canvas gets smaller.
Apply
Click Apply. The working area changes, the view fits the new canvas, and the dialog closes. Cancel, Escape, or a click outside leaves the photo as it was. Apply with the same width and height leaves it as it was, and the dialog stays open. Undo restores the previous canvas and the previous layer positions.
The pixels keep their size. Type moves with the picture and keeps its font size. A photo you open uses a transparent background, so a new margin shows the checkerboard. PNG and WebP keep those pixels clear. JPEG fills them with white. Fill paints the margin if you want a colour there. File → New can start with a solid background, and that colour fills the working area, including a margin you add later.
A smaller canvas keeps the layer pixels, and the part that no longer fits sits outside the working canvas, so an export of this document leaves it out. Undo brings the previous canvas back. Select (V) drags the layer if you want a different part inside the frame. Apply also clears a selection and any crop box.
Image Size scales every layer, including type. Crop redraws raster layers into the new frame and drops what sits outside the working canvas. In Export, Set canvas to this size appears when the download width or height differs from the document, and that button uses the centre anchor.
The same pixels, a new working area
After Canvas Size the document is the width and height you set, nothing was uploaded, and the picture kept its pixel size. If the margin is on the wrong side, undo and pick another anchor.
Download PNG, JPEG, or WebP if you need a file to send. Come back later and the document is still listed under the editor, until this browser’s storage is cleared. Canvas Size sits with the other photo editing tools: scale the picture the picture, crop the frame the frame, and export a listing.