Image Watermark and Stitching

Image Watermark and Stitching: Batch Watermarks and Multi-Image Composition

Adding a name or Logo watermark before publishing work, or combining several images into a comparison image or long image, are two very common needs. This tool puts watermarking and stitching into two tabs on the same page. Drag in images, set the parameters and click execute to get the result. Everything is processed locally in the browser, and images are not uploaded to the server.

Text and Image Watermarks

There are two watermark types. Text watermarks are suitable for names, URLs and copyright notices. You can set the text, font size, color, opacity, margin and rotation angle. Font size is calculated as a percentage of the image width, so the visual proportion remains consistent across images of different sizes. Image watermarks are suitable for Logos. A PNG with transparency works best, and its size is also controlled as a percentage of the image width. Both watermark types support nine positions (four corners, four edge centers and the exact center) as well as full-image tiling. Tiling repeats the watermark across the entire image at fixed intervals, which is useful for preventing reuse after cropping.

Live Preview and Batch Processing

After images are uploaded, a live preview appears immediately. The preview updates as watermark parameters are changed or images are switched, providing a what-you-see-is-what-you-get result. The preview is scaled proportionally, while watermark position and size match the final output. Multiple images can be dragged in at once. The list shows file names and sizes, and individual files can be removed. After clicking execute, images are processed one by one in order, with a progress bar showing the current progress and an option to cancel. With one image, a before-and-after comparison is shown. With multiple images, the interface switches to a table showing file name, original size, processed size and download buttons, with an All Download (ZIP) option for downloading everything as one archive.

Image Stitching

The stitching tab supports horizontal and vertical directions and combines images in the selected order. The order can be changed by dragging or reversed with one click. Common settings include image spacing, background color for filling gaps between images, alignment (center, top or left, bottom or right), and unified sizing. Horizontal stitching unifies height, while vertical stitching unifies width. You can keep the original sizes, unify by the smallest edge (reducing larger images), or unify by the largest edge (enlarging smaller images). The estimated output dimensions are shown before composition. If the result exceeds the browser processing limit of approximately 40 million pixels, processing is blocked and you are asked to reduce the number or size of images.

Output Format and Quality

The watermark tab supports Auto (keep the original format where possible), JPG, PNG and WebP. JPG and WebP quality can be adjusted, while PNG is lossless and automatically skips the quality setting. PNG is recommended when transparency needs to be preserved, while JPG or WebP can be used for photos to control file size. Stitching results can also be downloaded as PNG, JPG or WebP.

Errors and Use Cases

The tool provides clear messages when no images have been added, no watermark text has been entered, or no watermark image has been selected. Duplicate files are skipped with the count shown. GIF files use only the first frame. Suitable use cases include adding attribution watermarks to photography and illustrations, applying a brand Logo consistently to e-commerce images, combining comparison images into one long image, and stitching serialized comics vertically into a long image for publication.

Privacy and Data Security

Watermark compositing and image stitching are performed entirely in the browser. The page has no upload interface, images are not sent to the server or saved, and they are released from memory after the page is refreshed or closed.