RIOT 2026.9.1 – Free Image Optimizer

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2026-09-08 00:00 5858

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Description

Changelog

Specifications

RIOT (Radical Image Optimization Tool) is a free image optimizer that will let you to visually adjust compression parameters while keeping minimum file size. It uses with 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, number of colors, metadata settings and much more, and select image format (JPG, GIF or PNG) for your output file.

Also you can integrate RIOT as plug-in in well known programs like The GIMP, IrfanView and XnView.

Main features of RIOT:

open many image types including rare/scientific types
save and optimize JPEG, GIF, PNG and Web with a simple, clean user interface
automatic optimization selects the most suitable format and parameters
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
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).
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

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)

Changes in RIOT 2026.9 (2026-09-08):

Engine

Automatic image optimization presets: HQ, Standard, Eco 1, Eco 2, and Lossless.
Content analysis (colour count, texture, photo vs drawing, source quality) drives quality, chroma, and lossless vs lossy choices.
One worker per CPU core for parallel batches.
Optimal format: try a smaller container; keep the original when it is already smaller.
Original format: keep a supported source type.
Keep-original path when an auto re-encode is not smaller (after requested metadata stripping).

Formats

Open: JPEG, PNG, WebP, GIF, TIFF, HEIC, AVIF.
Save: JPEG, PNG, WebP, GIF (AVIF output not enabled in this release).
JPEG: quality, progressive, chroma subsample; high-efficiency encoding.
PNG: standard and maximum-compression passes; palette from analysis or quantization.
WebP: lossy, near-lossless, lossless; quality and effort.
GIF: keep or drop duplicate frames; animation keep or flatten.

Desktop

Batch list with size, status, output size, and savings.
Compare & preview: curtain, pan, zoom, hold-to-swap, animated playback.
Resize (px or %, aspect, upscale, filter) for any format.
Quantization for manual PNG / WebP / GIF.
Metadata, transparency, and animation panels.
Overwrite, backup, delete originals, keep timestamps (with confirmations).
Light / dark / system theme; English, Spanish, Romanian.
Help menu links to the User Portal for bugs and feature requests.

Homepage – https://riot-optimizer.com/

Supported Operating Systems: Windows 7, 8, 8.1, 10, 11.

Size: 42.2 MB