How to compress images without losing quality (and when you can't)

Truly lossless: PNG, WebP, GIF

These formats can be re-encoded so that every pixel is identical. A PNG written by a quick screenshot tool is often 10–30 % larger than it needs to be; ConvertX's "Exact quality" mode rewrites it with better compression and nothing else changes.

Not lossless: JPG, HEIC, AVIF

JPEG and its modern relatives are lossy by design. There is no way to make a JPG smaller without re-encoding it, and re-encoding always discards something. ConvertX is honest about this: in "Exact quality" mode a JPG is left untouched unless you resize it, and HEIC is saved as a maximum-quality JPG.

The practical answer is the Light preset: the loss exists but is below what you can see at normal sizes. Keep the original if you might compress again.

Resize first, then compress

A 12-megapixel photo is 4000 pixels wide. No screen shows that. Setting a maximum width of 2048 px cuts the file by about 75 % before any quality setting is applied, and the result still fills a 4K display. For messaging, 1600 px is plenty.

Which preset

• Light: best quality, modest savings. Printing and editing.
• Balanced: good quality, smaller files. The default for sharing.
• Strong: much smaller, visible on zoom. Thumbnails and previews.
• Maximum: smallest files, lower quality. Only when size is all that matters.

Step by step

1. 1

   Open Image Compressor

   On the Home screen, tap Image Compressor.

2. 2

   Select the images

   Tap "Select image files" and pick the photos or graphics.

3. 3

   Choose the mode

   Pick "Exact quality" for a lossless result (PNG, WebP, GIF), or "Smaller files" with the Light preset for photos.

4. 4

   Check the estimate

   Read the estimated size for one file. If it isn't small enough, set a maximum width before touching the quality.

5. 5

   Run the batch

   Tap "Compress N images" and collect the results from the Library.

Frequently asked questions