A photo straight from a camera or phone routinely weighs 2–5 MB. Put a few of those on a web page and the page gets slow — especially for visitors on mobile connections. Image compression is how you fix that: the picture keeps its dimensions and looks essentially the same, while the file gets dramatically smaller.
Rather than repeat the usual claims, we tested Pixora's Image Compressor with our own files and measured everything ourselves: exact bytes before and after, dimensions, and an objective quality score for each result. This walkthrough shows the workflow, the real numbers we got, and one honest quirk you should know about before batch-compressing your library.
What compression actually does
Most image compression for the web is lossy: the encoder discards some of the finest detail — the kind your eye barely registers in a photograph — and stores the rest more efficiently. Two decisions control the outcome:
- Format. JPG is the universal photo format. WebP is a newer format that usually reaches a smaller file than JPG at a similar quality level. PNG is lossless and best for graphics that must stay pixel-perfect, but it produces heavy files for photos. AVIF is the newest option, with support still growing.
- Quality. A slider, typically 1–100. Higher quality keeps more detail and more bytes; lower quality shrinks the file further but eventually produces visible softness or blocky artifacts. The skill is picking the point where the saving is large and the difference is not.
Compression is not resizing: the width and height in pixels stay exactly the same unless you separately choose to resize.
The tool at a glance
Pixora's compressor runs in the browser. You add images by dragging them in, clicking Select files from device, or pasting from the clipboard with Ctrl+V. You then pick an output format — Keep Original Format (Smart Automatic), WebP, JPG, PNG, or AVIF — set a quality value (the default is 60), or switch on Auto-Tune Quality and let the tool choose. Clicking Start processing now compresses the batch; each result can be downloaded individually, or all together with Download All as ZIP. Compressed files get a _min suffix, so originals are never overwritten. In our testing the tool was free and needed no sign-in; Pixora states that processing happens entirely in your browser and files are never uploaded to a server.
Step by step
- Open the Image Compressor and add your image (drag, browse, or paste).
- Choose the output format explicitly — WebP for the smallest web files, JPG if you need maximum compatibility (why "explicitly" matters is explained below).
- Set quality: 80 is a safe starting point for photos; or enable Auto-Tune Quality if you would rather not think about it.
- Click Start processing now. The tool shows the original size, the compressed size, and the percentage saved for each file.
- Download the results one by one, or as a single ZIP for a batch.
Our test results
Our main test file was a photo-like JPEG of 2400×1600 pixels weighing 2,225,398 bytes (about 2.2 MB). We also used a sharp text graphic saved as a PNG (16,028 bytes) — the hardest case for compression, because text edges show artifacts first. Quality is reported as PSNR, a standard objective score comparing the compressed image with the original; as a rough guide, above 30 dB a photo is very hard to tell apart from the original in normal viewing, and above 40 dB is near-identical.
| Test | Setting | Before | After | Saved | Quality (PSNR) |
|---|---|---|---|---|---|
| Photo | WebP, Auto-Tune | 2,225,398 B | 572,008 B | 74.3% | 31.6 dB |
| Photo | JPG, quality 80 | 2,225,398 B | 846,031 B | 62.0% | 30.9 dB |
| Photo | WebP, quality 50 | 2,225,398 B | 419,338 B | 81.2% | 30.6 dB |
| Text graphic (PNG) | WebP, quality 80 | 16,028 B | 9,466 B | 40.9% | 42.4 dB |
Three things stand out. First, every setting kept the dimensions identical and produced a file that scored at or above roughly 30 dB — the savings are real, not bought with obvious damage. Second, WebP beat JPG clearly on the same photo: even at quality 50 it produced a smaller file than JPG at quality 80, with a similar quality score. Third, Auto-Tune landed sensibly in the middle (74.3% saved), which makes it a reasonable default if you do not want to experiment. And on the text graphic, the WebP result was near-identical to the original — in a side-by-side crop at 200% zoom, we could not tell the compressed text from the original — while still cutting 41% of the size.
One quirk to watch in batch mode
In our batch test we left the format on Keep Original Format (Smart Automatic) with the default quality of 60. The photo compressed properly (81.0% saved). But our two small PNG files came back byte-for-byte identical to the originals — yet renamed with a .jpg extension, even though their content was still PNG data. A file whose extension lies about its format can confuse some tools and uploads. The fix is simple: choose the output format explicitly (WebP, JPG, or PNG) instead of relying on the automatic option, and spot-check your first batch before trusting it with a whole folder.
Which settings should you use?
- Blog and website photos: WebP at quality 80, or Auto-Tune — large savings, no visible difference in our tests.
- Maximum compatibility (email, older software, uploads that reject WebP): JPG at quality 80.
- Smallest possible file for thumbnails or previews: WebP at quality 50 — still scored above 30 dB on our photo, but check faces and fine detail at 100% zoom before publishing.
- Graphics with text or sharp edges: WebP at quality 80 worked near-perfectly in our test. If a graphic must stay absolutely untouched, keep the original PNG and skip compression.
- Always keep your originals. Compression is one-way; the
_mincopies are for publishing, not for your archive.
Quick answers
Does compression change the image dimensions? No. In every test the output kept the exact pixel dimensions of the input. Changing dimensions is a separate job (Pixora offers a dedicated Image Resizer for that).
Is the tool really free? It was free and worked without an account throughout our testing.
Should I compress photos that carry location data? Compression is about size, not privacy — and re-encoding is not a reliable way to strip metadata. If a photo contains GPS data, clean it deliberately first; our guide to removing EXIF and GPS location data shows how, with the same verify-it-yourself approach used here.
References
- Pixora — Smart Image Compressor (hands-on testing performed 1–2 November 2026; all figures in the table are our own measurements on the test files described above).