Image Resizer
Image Resizer makes smaller (or bigger) copies of many pictures at once: for email, a website, a phone, or just to save space. It writes the copy next to each original and never changes the original.
Use it, step by step#
- Open Image Resizer.
- Add the pictures. Drop them on Drop Pictures Here, or click Choose Pictures… and select them (several at once). Each one appears in the Pictures list with its size in pixels and its file size. Add more at any time. The trash button on a row takes that picture out of the list, and Clear empties the list.
- Choose the size in the panels on the right (see below), or click one of the ideas under Which size should I use? to set it for you.
- Click Resize. The button says how many pictures it will do (Resize 3 Pictures). Each row shows its progress and then its result: the old and new size in pixels, the file size before and after, and the name of the new file.
- Find the copies beside the originals, named
name (WxH).ext.beach.jpgresized to 1920 × 1440 becomesbeach (1920x1440).jpg. A copy never replaces a file: if the name is taken it becomesbeach (1920x1440) 2.jpg.
Nothing is resized until you click Resize, so you can add pictures and change the settings in any order.
Want a different size too? Change the size and click Resize Again: it makes new copies of everything in the list with the current settings. The originals are never touched, and the earlier copies stay.
Supported pictures: PNG, JPEG, WebP, GIF, BMP and TIFF. Dropped files of other kinds are ignored.
Which size should I use?#
Click an idea to set the controls, then click Resize.
| Idea | What it sets | Good for |
|---|---|---|
| Email or chat | Medium: 1280 px on the longest side | Pictures small enough to send that still look sharp on a screen |
| Website or blog | Large: 1920 px on the longest side | A full-width page |
| A post for social media | Width 1080 px, height open (0) | Feeds that scale to 1080 px wide |
| A square thumbnail | 256 × 256 px, Fill the size and trim the edges | Avatars and small previews |
| A phone wallpaper | 1080 × 2400 px, Fill the size and trim the edges | A tall phone screen |
| A 4 × 6 inch print | 1800 × 1200 px (300 dots per inch), Fit inside the size | Photo prints |
| Half the size | 50 percent | Any picture you just want smaller |
Not sure? Large: 1920 px is a good default for sharing, and Medium: 1280 px for email.
Size#
Make the pictures offers these choices (or use an idea above):
| Choice | Result |
|---|---|
| Small: 640 px on the longest side | The longest side becomes 640 px, keeping the shape |
| Medium: 1280 px… | 1280 px |
| Large: 1920 px… (the default) | 1920 px |
| Very large: 3840 px… | 3840 px |
| A share of their size | Percent of the original, from 1 to 500 |
| A width and height | Width (px) and Height (px); 0 leaves one open and the other follows the shape. Choose When the shape is different: Fit inside the size, Fill the size and trim the edges (the middle is kept), or Stretch to exactly that size |
Allow enlarging is off by default: a picture smaller than the size you asked for is left at its own size. Turn it on to make small pictures bigger (they get blurry).
Output#
| Control | What it does |
|---|---|
| Format | Same as the original, PNG, JPEG or WebP. WebP needs the WebP pixbuf loader on your system; if it is missing, Voltkit tells you which package to install. |
| Quality | 1 to 100 for JPEG and WebP (default 90). PNG is always lossless. |
What happens to the picture#
- Rotation is applied. A photo taken sideways (its EXIF orientation) comes out upright.
- Other metadata is not copied into the new file, so details such as where a photo was taken are left out.
- The original is never opened for writing.
From the terminal#
voltkit resize photos/*.jpg --longest-side 1280
voltkit resize *.png --percent 50
voltkit resize banner.jpg --width 1200 --height 400 --mode fill
voltkit resize *.png --longest-side 800 --format webp --quality 85Choose the size with --longest-side, --percent, or --width and/or --height (default: --longest-side 1920). Other options: --mode fit|fill|stretch, --enlarge, --format same|png|jpeg|webp, --quality N. The command prints each result with its sizes and file sizes, and exits with an error if any picture failed.
Troubleshooting#
- A format fails. This computer can't write WebP pictures means the WebP pixbuf loader is missing (package
webp-pixbuf-loader). - Nothing happens when I add pictures. That is expected: add them, then click Resize.
- The picture did not get smaller. It may already be smaller than the size you asked for: turn on Allow enlarging, or choose a smaller size.
- A file is not accepted. Only PNG, JPEG, WebP, GIF, BMP and TIFF pictures are resized.