IBC – Image Batch Converter

User Manual

Overview

IBC (Image Batch Converter) lets you convert, resize, and rename large numbers of images in one go — all inside your browser tab. It uses the HTML5 Canvas API to decode and re-encode images, so nothing ever leaves your device. Your settings (format, quality, resize mode, rename config) are saved automatically in localStorage and restored on your next visit.

Getting Started

Loading images

Drag & drop — drag one or more image files from your file manager directly onto the drop zone at the top-left of the app.
Browse — click the Browse Files button to open a system file picker. You can select multiple files at once.

Supported input formats: .jpg, .png, .webp, .avif, .bmp, .tiff, .gif, and any other format your browser can decode.

You can add more files at any time — new files are appended to the existing list.

Converting and downloading

Configure the output settings in the right sidebar (format, resize, rename, output destination).
Click ⚡ Convert All in the bottom-right corner to process all files.
Each file's status updates in real time: Pending → Converting → Done / Error.
When done, the output is downloaded automatically as a ZIP file (or saved to your chosen folder in Chrome/Edge).

File List

Each loaded file shows a thumbnail, filename, dimensions, and file size. The right side shows the conversion status badge. Click × on any row to remove that file. Use Select All to highlight all rows, or Clear List to remove everything and start over.

Output Format Panel

Setting	Description
Format	Target format for all converted images. Options: JPEG, PNG, WebP, BMP, TIFF, GIF.
Quality	Compression quality (1–100%). Only shown for JPEG and WebP — both support lossy encoding. Higher = larger file, better quality. PNG, BMP, TIFF, and GIF are lossless.

TIFF and BMP files saved via Canvas are uncompressed and can be large. Use PNG for lossless compression.

Resize Panel

Toggle Enable resizing to activate. Choose one of six resize modes:

Mode	Behaviour
Exact dimensions	Resize to the exact width × height you specify. If Maintain aspect ratio is checked, the image is scaled to fit within those dimensions while keeping its proportions.
Fit within (keep aspect)	Scale the image down (or up) so it fits inside the bounding box, always preserving the aspect ratio. The output will not exceed the specified width or height.
Fill and crop (cover)	Scale the image so it fully covers the target dimensions, then centre-crop to fit exactly. Useful for thumbnails.
Scale by percentage	Scale the image by a percentage of its original size (e.g. 50% halves both dimensions).
Width only (auto height)	Set a fixed width; height is calculated automatically to maintain the aspect ratio.
Height only (auto width)	Set a fixed height; width is calculated automatically to maintain the aspect ratio.

Never upscale images — when checked, images that are already smaller than the target dimensions are not enlarged.

Rename Panel

Toggle Enable renaming to activate. By default, converted files keep their original name with the new extension.

Setting	Description
Prefix	Text added before the filename (e.g. `photo_`).
Suffix	Text added after the filename, before the extension (e.g. `_final`).
Add sequential number	Appends a zero-padded number (e.g. `001`, `002`) after the prefix. The start number is configurable.
Preview	Shows a live example of what the first output filename will look like.

With sequential numbering enabled and no prefix/suffix, files are simply numbered: 001.jpg, 002.jpg, etc.

Output Panel

Option	Description
Download as ZIP	All converted images are bundled into a single `converted-images.zip` file and downloaded automatically. Works in all browsers.
Save to folder	Only shown in Chrome and Edge (requires the File System Access API). Click Browse to pick an output folder on your computer — files are saved there directly without a ZIP.

Privacy

IBC processes everything locally in your browser using the Canvas API and File API. No images, filenames, or settings are ever transmitted to any server. Your configuration is saved in localStorage in your browser and never leaves your device. The only external resource loaded is the JSZip library from cdnjs.cloudflare.com (fetched once, on first conversion).

Supported File Types

Input: any format your browser can decode — typically .jpg · .png · .webp · .avif · .bmp · .tiff · .gif

Output: .jpg · .png · .webp · .bmp · .tiff · .gif

AVIF output is not supported — Canvas toBlob() cannot encode AVIF in current browsers. AVIF images can still be used as input.

GIF output via Canvas produces a static image (single frame). Animated GIFs are not supported as output.

About this tool

Technologies used:

Built with:

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