FastStone Image Viewer is a Windows program for browsing photo folders, comparing pictures, making corrections and converting image collections. It combines a thumbnail browser with a full-screen viewer, so choosing photographs and editing them can happen within the same application. It is free for personal and educational use; commercial use requires a license.
Browsing photos with FastStone Image Viewer
The folder browser uses an Explorer-style layout with thumbnails and an image preview. Opening a photograph in full screen gives the image most of the display, while moving the pointer to a screen edge reveals panels for the thumbnail browser, EXIF information and editing commands. This keeps neighboring photographs and their camera information accessible while inspecting the current picture.
FastStone Image Viewer can switch between fitting the whole picture on screen and showing it at actual size. Its configurable magnifier enlarges a smaller area for closer inspection. With two monitors, the thumbnail browser can occupy one display while the full-screen preview appears on the other.
Supported inputs include JPEG, PNG, TIFF, HEIC, WebP and PSD, along with camera RAW formats such as CR3, NEF, ARW and DNG. The viewer also opens PDF files, SVG graphics and JPEG XL images.
Image selection
The comparison tool displays up to four images side by side. Tags and ratings from one to five provide separate ways to mark files, and the browser can sort by rating, tagged status or the date a photograph was taken.
Tagged files can be isolated for operations such as copying, moving, editing or running a slideshow. Drag-and-drop also handles copying, moving and rearranging files. FastStone Image Viewer keeps tags and ratings in its database when files are copied or moved through the program.
RAW settings can hide RAW files from the browser while keeping paired RAW and JPEG files together for renaming, copying, moving or deletion. This matters for cameras that record both forms of each photograph: selecting the visible JPEG can still include its RAW partner in those file operations. External editors can be configured for opening RAW files or sending an image to another application with a shortcut.
Photo correction
Cropping changes the picture’s boundaries, while resizing offers a choice of resampling algorithms for changing its pixel dimensions. The Straighten/Rotate tool can calculate a rotation from a line traced along a horizon or building edge. Rotation and cropping share the same window, so the image can be straightened and its resulting borders trimmed together. Lossless JPEG rotation and cropping are also available.
Lighting controls address shadows and highlights, while color, levels and curves adjustments alter the picture’s tonal rendering. These adjustments can be applied within selected areas rather than across the entire image. Sharpening, blurring and red-eye removal handle other corrections, with multiple undo and redo levels for revisiting changes.
The Draw Board adds text, lines, highlighted areas, shapes and callouts to an image. Text can have outlines or shadows, and framing and color effects provide further changes to the finished picture.
Batch conversion
FastStone Image Viewer processes selected collections through its Batch Convert/Rename tools. Filename templates control the names assigned to the results, while conversion settings apply repeated image changes across the selection. Advanced adjustments include shadows and highlights; resizing can be configured to leave pictures alone when they are already smaller than the requested dimensions.
Date-based renaming can use the EXIF capture time in HEIC and HEIF photographs when that information is present. For an individual image, the Save As interface previews the effect of output settings on picture quality and generated file size.
Slideshows, contact sheets and print layouts
Slideshows play selected photographs with transition effects and optional music in formats including MP3, WMA and WAV. A slideshow can use the secondary monitor, leaving the other display available for the browser.
Contact sheets arrange image thumbnails into a configurable sheet. The Design and Print tool handles a different output: multiple images laid out on a printed page with text and effects. Captions can include properties such as filenames, capture dates and dimensions, giving printed photographs identifying information beneath them.
Scanning
FastStone Image Viewer also acquires pictures from a scanner. Its scanning tool supports batch capture to PDF, TIFF, JPEG and PNG, with rotation, cropping, deskewing and annotation available before saving. Scanned images can also be printed or prepared for email from within that tool.
