Compression Presets Explained — Gentle, Smart, Tiny & Auto Quality
Image compression is a trade-off between file size and visual quality. MiniPx simplifies this trade-off into four options: Gentle, Smart, Tiny, and Auto Quality. Each targets a different point on the quality-size curve, so you never need to guess a numeric quality slider value.
How compression works (30-second version)
JPEG compression works by dividing your image into 8x8 pixel blocks, converting colour data into frequency components, and discarding information your eyes are least likely to notice. The more you discard, the smaller the file — but eventually you start seeing blocky artifacts and colour banding.
PNG compression is lossless — it reduces file size through efficient encoding without removing any image data. WebP and AVIF use more advanced algorithms that achieve smaller files than JPEG at the same visual quality, giving you more room to compress without visible loss.
Gentle — maximum quality, modest reduction
Gentle keeps quality as high as possible while still reducing file size. It typically achieves 20-40% reduction. The output is visually identical to the original at any zoom level. Pixel-level differences exist but are invisible to the human eye.
Use Gentle when: uploading portfolio work, compressing client deliverables, preparing images for print, or any context where someone might inspect quality closely. Also appropriate for medical images, technical diagrams, and product photography where detail preservation matters.
Smart — balanced compression for everyday use
Smart is the default recommendation. It achieves 50-70% file size reduction while keeping quality high enough that casual viewers cannot tell the difference. On a typical screen at normal viewing distance, Smart output looks identical to the original.
Use Smart when: uploading to a website or blog, emailing photos, posting to social media, adding images to documents, or compressing for any general-purpose use where you want small files without obvious quality loss.
Tiny — smallest possible file size
Tiny applies aggressive compression to minimise file size regardless of visible quality loss. Reductions of 70-90% are common. At full zoom, you will see compression artifacts — blocky areas, colour banding, and softened edges. At small display sizes (thumbnails, preview grids, avatars), these artifacts are invisible.
Use Tiny when: generating thumbnails, creating preview images, compressing for bandwidth-constrained environments (slow connections, data caps), meeting strict file size limits on government forms or exam portals, or when you genuinely need the smallest possible file.
Auto Quality — let the algorithm decide
Auto Quality analyses each image individually before compressing. It looks at colour complexity (photos with many gradients need more data than flat illustrations), detail density (high-detail images degrade more visibly), and format characteristics. Based on this analysis, it picks the quality level that produces the smallest file where loss is not visible at normal viewing distance.
Use Auto Quality when: you are processing many different types of images and do not want to pick settings manually for each one. It works well for batch processing where images vary — a mix of photos, screenshots, illustrations, and diagrams that each need different compression levels.
Quick reference
| Preset | Reduction | Quality | Best for |
|---|---|---|---|
| Gentle | 20-40% | Indistinguishable | Portfolio, print, clients |
| Smart | 50-70% | Visually identical | Web, email, social |
| Tiny | 70-90% | Visible at full zoom | Thumbnails, forms, limits |
| Auto | Varies per image | Optimal balance | Batch, mixed content |
Format matters more than level
Choosing the right format often saves more space than choosing aggressive compression. A photo exported as WebP at Smart quality will typically be 25-35% smaller than the same photo as JPEG at Tiny quality — with better visual quality. AVIF pushes this further: Smart AVIF is often smaller than Tiny JPEG.
If your target platform supports WebP or AVIF (most modern browsers do), switching format is a better first move than cranking compression to maximum. You get smaller files and better quality simultaneously.
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