Worked usage and result checks

Compose a fixed-size raster collage

Online Collage Maker places up to four local images into one of four fixed arrangements. The canvas is 1,600 by 1,200 pixels. You can adjust the space between slots, corner rounding, background and export format while keeping the same workspace. This is a slot-based composition tool rather than a freeform layer editor or a way to merge source images at their original sizes. A template determines how many slots are visible; selecting a two-slot arrangement does not delete third and fourth images from the selection. Those extra sources can reappear when a larger arrangement is chosen.

Worked example with controlled source colors

Prepare two images you own: one solid red rectangle and one solid blue rectangle. Add red first and blue second, choose the side-by-side two-image template, and reduce corner rounding to zero. The first selected image should occupy the left slot and the second the right slot, with the chosen background visible in the margins. Download PNG and reopen it in a separate image viewer. Check that its dimensions are exactly 1,600 by 1,200, that the slot colors remain red and blue and that neither source was reordered by its decoding speed. The saved pixels provide a stronger check than a success notification.

Selection limits and invalid files

Choose PNG, JPEG or WebP files up to ten MiB each. A decoded source must fit within 16,384 pixels per side and twenty million pixels. The collage accepts at most four images in total. Selecting more than the remaining capacity produces an error rather than silently dropping the extras. If any file in a new selection cannot be read or decoded, that selection is not partially appended. Existing successfully selected images remain available, while the error explains why the new selection failed. Remove or clear sources deliberately before retrying. The file input resets after a selection so the same file can be chosen again after clearing the layout.

Templates and the meaning of source order

The side-by-side template uses two columns; the top-and-bottom template uses two rows. Hero Focus uses a larger left image with two stacked images on the right. Equal Grid uses four cells in a two-by-two arrangement. File order assigns images to these slots, so inspect the preview after selecting sources. This page does not provide drag-to-reorder or independent pan controls within each cell. To change the assignment, remove the relevant sources and select the desired files in the intended order. A partially filled template shows the background in unoccupied cells instead of inventing or duplicating a photograph to fill them.

Understand center cropping before exporting

Each source is scaled to cover its assigned cell while preserving aspect ratio. Any part extending beyond the cell is clipped. A very wide photograph in a tall slot therefore loses content from its sides, and a tall photograph in a wide slot can lose content from the top and bottom. Corner rounding clips the slot further. This behavior avoids stretching faces or circles into a different shape, but it can hide a caption near an edge. Inspect important subjects and embedded text at the actual cell boundaries. If the crop is unsuitable, prepare a different source crop or choose another template; the gap slider cannot change the source's focal point.

Gap, background and empty space

Inner Gap Spacing ranges from zero to sixty pixels. It changes both the separation between slots and the framing space around the canvas. Corner rounding ranges from zero to fifty pixels. The background accepts a six-digit hexadecimal color and fills exposed margins and empty cells. Keep a controlled test with a high-contrast background when verifying layout geometry. Because the output size is fixed, increasing the gap reduces the space available to each image rather than enlarging the exported canvas. A background choice that appears attractive in the editor still needs inspection in the receiving document, especially if that document adds its own border or background.

Export a real supported format

PNG is lossless for the rendered collage, JPEG applies lossy compression and WebP depends on the browser's encoder. The export checks that the returned file type matches the selected format rather than saving a PNG under a WebP filename. Export is disabled while new sources are loading or the current canvas is not ready. If the layout changes during encoding, retry the current layout instead of handing off the stale file. Reopen the actual saved file and compare its dimensions and visible crop. A fixed output canvas does not restore detail that was absent from a small source, and JPEG can soften fine text even when its filename is correct.

Local processing and troubleshooting

Source reading, image decoding, center cropping and encoding happen in this browser. No collage-processing API is used, while the surrounding site can still load ordinary assets and services under its Privacy Policy. The tool does not save a reusable project, so keep original images and record important settings before leaving. If a selection fails, retry one small known PNG and read the error before adding other sources. If the preview seems out of order, clear it and select the red/blue fixture in a known sequence. If export fails, try PNG, reduce source dimensions and close unnecessary memory-heavy tabs. Use only images you are entitled to edit and distribute; composition does not grant a source-image license.

Online Collage Maker — Create Custom Image Grid Collages