Redimages: A Lightweight Batch Image Resizer for Ubuntu

Batch image resizing is one of those tasks that comes up constantly — preparing thumbnails for a website, shrinking photos before emailing, normalising dimensions for a slideshow — and most people resort to opening GIMP and processing files one by one. Redimages was built specifically to eliminate that tedium. It is a small GTK application for Ubuntu that takes a folder of images, applies your target dimensions and quality settings, and writes the results to an output directory in seconds. No scripting, no command-line flags, no GIMP macros.

What Redimages Does

Redimages focuses on a single workflow: resize many images at once. Its feature set is deliberately narrow:

• Batch queue. Add individual files or an entire directory. Redimages lists every image with its current dimensions and file size.
• Resize modes. Choose between exact pixel dimensions, percentage scaling, or fitting within a bounding box while preserving aspect ratio.
• Output format. Save as JPEG (with adjustable quality), PNG, BMP, or TIFF.
• Output directory. Write resized images to a separate folder or alongside the originals with a configurable filename suffix.
• Preview. Thumbnail preview of each image before processing.

It does not crop, rotate, apply filters, or edit metadata. It resizes — and it does so quickly because it avoids loading a full image-editing toolkit.

Step-by-Step Installation

Method 1: PPA

The easiest approach on Ubuntu 12.04 and 11.10:

sudo add-apt-repository ppa:dhor/myway
sudo apt-get update
sudo apt-get install redimages

Verify installation:

which redimages
redimages --version

Method 2: Download the .deb Package

If you prefer not to add a PPA:

1. Download the .deb file for your architecture from the PPA’s package listing page.
2. Install with dpkg:

sudo dpkg -i redimages_*.deb
sudo apt-get install -f

The apt-get install -f command resolves any missing dependencies that dpkg flagged.

Launch

Open Redimages from the application menu under Graphics → Redimages, or run:

redimages &

Step-by-Step Batch Resize Workflow

1. Add Images to the Queue

Click Add Files to select individual images, or Add Folder to load every supported image in a directory. The file list populates with filenames, dimensions, and sizes.

2. Set Target Dimensions

Choose one of the resize modes:

• Exact size — Specify width and height in pixels. The image is stretched or squashed to fit (aspect ratio is not preserved).
• Percentage — Scale by a percentage of the original dimensions. 50 % halves both width and height.
• Fit within — Specify a maximum width and height. The image is scaled down proportionally so that it fits inside the bounding box. Images smaller than the bounding box are left untouched.

For most web workflows, Fit within 1200 × 1200 at JPEG quality 85 is a solid default.

3. Configure Output

• Output directory. Click Browse and select or create a destination folder.
• Output format. Select JPEG, PNG, BMP, or TIFF from the dropdown.
• JPEG quality. Slide the quality bar. 85 is a good balance between file size and visual fidelity. Below 70, JPEG compression artefacts become visible on detailed images.
• Filename suffix. Optionally append a suffix like _resized to prevent name collisions.

4. Process

Click Start. A progress bar tracks completion. On a typical Core i5 system, Redimages processes roughly 50–80 JPEG images per minute at 1200 px wide.

5. Verify Output

Spot-check a few resized images:

identify output/photo_001.jpg

The identify command (from ImageMagick) prints dimensions and file size. Confirm they match your target.

Comparison: Redimages vs ImageMagick convert

ImageMagick’s convert (or mogrify for in-place operations) is the de facto command-line image processor on Linux. How does Redimages stack up?

Verdict: Redimages wins on convenience for simple resize-only tasks. ImageMagick wins on flexibility, format support, and resize quality (Lanczos resampling produces sharper results than GDK Pixbuf’s bilinear filter on downscaled images).

ImageMagick Equivalent Command

To replicate a Redimages “fit within 1200×1200, JPEG quality 85” batch job on the command line:

mkdir -p output
for img in *.jpg; do
  convert "$img" -resize 1200x1200\> -quality 85 "output/$img"
done

The \> flag tells ImageMagick to only shrink images larger than the target — exactly matching Redimages’ “fit within” behaviour.

Mogrify for In-Place Resizing

If you want to overwrite the originals (dangerous — back up first):

mogrify -resize 1200x1200\> -quality 85 *.jpg

Scripting Alternatives

For users comfortable with the terminal, a pure Bash script offers maximum control:

#!/bin/bash
INPUT_DIR="$1"
OUTPUT_DIR="$2"
MAX_DIM="${3:-1200}"
QUALITY="${4:-85}"

mkdir -p "$OUTPUT_DIR"

for img in "$INPUT_DIR"/*.{jpg,jpeg,png,JPG,JPEG,PNG}; do
  [ -f "$img" ] || continue
  filename=$(basename "$img")
  convert "$img" -resize "${MAX_DIM}x${MAX_DIM}>" -quality "$QUALITY" "$OUTPUT_DIR/$filename"
  echo "Resized: $filename"
done

Save as batch-resize.sh, make executable, and run:

chmod +x batch-resize.sh
./batch-resize.sh ~/Photos ~/Photos/resized 800 80

This resizes all images in ~/Photos to fit within 800×800 at quality 80, writing output to ~/Photos/resized.

Common Pitfalls

1. Adding the wrong PPA for your Ubuntu version. Confirm the PPA lists packages for your release codename (precise for 12.04, oneiric for 11.10). Installing packages built for a different release can break library dependencies.
2. Setting “Exact size” when you mean “Fit within.” Exact size ignores aspect ratio and distorts images. Unless you are generating fixed-size tiles, you almost always want the aspect-preserving “Fit within” mode.
3. Choosing JPEG quality above 95. Quality values above 95 produce diminishing visual returns but dramatically increase file size. For web use, 80-85 is the sweet spot. For archival use, stay with PNG.
4. Overwriting originals by setting the output directory to the source directory. Redimages does not warn aggressively about this. Always point the output to a different folder and verify results before deleting originals.
5. Ignoring EXIF orientation. Redimages and basic ImageMagick convert calls may not auto-rotate images based on EXIF orientation data. Pre-process with:

   mogrify -auto-orient *.jpg
   

   before resizing to avoid sideways thumbnails.
6. Processing RAW files. Redimages does not support camera RAW formats (CR2, NEF, ARW). Convert to JPEG or TIFF first using dcraw or ufraw-batch:

   ufraw-batch --out-type=jpeg --out-path=converted/ *.CR2
   

When to Use Redimages vs the Alternatives

Choose Redimages when you need a quick, visual batch resize with no scripting and no terminal — ideal for non-technical users or one-off tasks. Choose ImageMagick when you need superior resize quality, format flexibility, or automation via cron jobs and scripts. Choose a custom Bash script when you need repeatable, version-controlled workflows integrated into a larger pipeline.