RIOT is a free image optimizer that will let you adjust compression parameters visually while keeping minimum filesize.

The Radical Image Optimization Tool (RIOT for short) was developed as a free image optimizer that will let you visually adjust compression parameters while keeping minimum files.

It uses a side by side (dual view) or single view interface to compare the original with the optimized image in real-time and instantly see the resulting file size.

It is lightweight, fast, and simple to use, yet powerful for advanced users. You will be able to control compression, the number of colors, metadata settings, and much more, and select image format (JPG, GIF, or PNG) for your output file.

Input image types:

common bitmap images as well as Adobe Photoshop PSD files

popular HDR formats and RAW camera images

rare / scientific types (up to 128 bpp, integer and floating point)

RIOT Features:

open many image types including rare/scientific types

save and optimize JPEG, GIF and PNG with a simple, clean user interface

works in dual view: (original optimized image) or single view (optimized image).

Automatic preview of resulting image

in-place compare function (alternativelly display the original image over the optimized image to notice small pixel changes)

compress files to desired filesize threshold

fast processing (all is done in memory);

see instant results including resulting filesize

batch support (process multiple files at once)

transparency handling options

decide if you want to keep metadata (comments, IPTC, Adobe XMP, EXIF profiles, ICC profiles).

Unsupported metadata is removed

transfer metadata between image formats (destination format must support them)

common tools: pan and zoom, rotate, flip

basic image adjustments: brightness, contrast, gamma, invert

visually reduce number of unique colors for PNG and GIF images in order to reduce filesize

(two quantization methods are available: Xiaolin Wu and NeuQuant neural net)

resize image by using well known resample filters (ex: Lanczos3, Catmull Rom, Bicubic, and others)

out-of-the-box support for external PNG optimizers (optipng, pngout, etc)

the compression and the results are comparable to those of commercial products, even higher.

Adaptive logarithmic tone mapping algorithm (Drago) used for HDR images

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