Lossy vs Lossless Compression
Understand lossy and lossless file compression for JPEG, PNG, MP4, PDF, and audio, and when each approach fits your workflow.
Design exports a PNG at 12 MB. Marketing needs a 500 KB hero image. Same photo, two different compression philosophies.
Archiving contracts as lossless PDF while emailing lossy review copies is standard in legal and product workflows. The word “compression” covers both behaviors.
Two strategies for smaller files
Lossless compression finds patterns in data and encodes them efficiently. Decode the file and you get the exact same pixels, samples, or vectors as before.
Lossy compression removes information the format considers less important. Decode and you get something extremely close visually, but not bit-identical to the source.
Neither is “better.” They serve different stages of a workflow.
The same photo can exist as a 50 MB RAW, a 12 MB lossless PNG, and a 400 KB JPEG. Each step trades fidelity for portability.
Lossless compression explained
Examples:
| Format | Lossless? |
|---|---|
| PNG | Yes (pixel-perfect) |
| FLAC audio | Yes |
| ZIP on text | Yes |
| GIF (256 colors) | Lossless for indexed colors, but palette reduction is lossy |
| H.264 at very high bitrate | Visually near-lossless, technically lossy |
Lossless shines when you might edit again, zoom crops, or archive legal originals. File sizes shrink modestly compared with lossy exports.
Text, flat graphics, and screenshots with hard edges favor lossless formats. Photos with millions of colors rarely compress losslessly to email-friendly sizes.
Lossy compression explained
Examples:
| Format | Typical lossy behavior |
|---|---|
| JPEG | Blends color, drops high frequency detail |
| WebP (lossy mode) | Similar goals to JPEG, often smaller |
| MP4 / MOV video | Discards imperceptible motion and texture |
| AAC / MP3 audio | Removes masked frequencies |
| PDF with downsampled images | Loses resolution in embedded photos |
Lossy settings use quality sliders, CRF, or target file size on video. Aggressive settings show banding, mosquito noise, or blocky video.
Transparency in PNG stays lossless; flattening to JPEG for email destroys alpha permanently. Plan format before the first client send.
Lossy vs lossless by media type
Images
- PNG, TIFF lossless: UI shots, logos, transparency. For web delivery, optimize images for web on Mac picks the right lossy export.
- JPEG, lossy WebP: photos for web and email. See compress JPG on Mac for quality presets.
- See how to compress images on Mac or the Windows image guide . Lossless PNG exports with metadata can shrink further with remove EXIF from photos on Mac .
Video
- All mainstream delivery codecs (H.264, HEVC, VP9, AV1) are lossy.
- “Visually lossless” exports use high bitrate for editing intermediates.
- See compress video without losing quality .
Audio
- WAV and FLAC for masters.
- AAC and MP3 for sharing.
Podcast hosts often archive WAV or FLAC while distributing MP3 or AAC to listeners. Same episode, two compression strategies.
- Vector text stays sharp.
- Embedded photos can be losslessly packed or lossily downsampled.
- See how to compress PDF on Mac . Upload portals often share email caps; compress PDF for upload limits on Mac targets those ceilings.
Generational loss and re-saving
Opening a JPEG, editing one pixel, and saving again re-compresses the whole image. Repeat ten times and banding grows. Keep a PNG or RAW master; export lossy copies for delivery.
Video suffers the same way. Re-encoding an MP4 for Slack, then again for email, stacks artifacts. Transcode once from the master.
Lossless PNG screenshots re-saved as PNG do not degrade. Converting PNG to JPEG is a one-way lossy step.
Version control repositories are a special case. Committing huge binary exports bloats history. Store masters outside git; commit compressed previews only when necessary.
How to pick for your task
| Scenario | Approach |
|---|---|
| Client logo with transparency | Lossless PNG; see compress PNG on Mac for palette-heavy artwork |
| Blog hero photo | Lossy JPEG or WebP at 80 to 85 quality |
| Legal scan archive | Lossless PDF or TIFF |
| Slide deck email | Lossy image downsampling inside PDF |
| Bug video attachment | Lossy H.264 720p from screen recording master |
| Family video archive | High-bitrate lossy or camera native; avoid repeated re-encode |
When in doubt, keep the lossless or high-quality master on disk and generate a lossy copy named for the channel (client-review.jpg, email-clip.mp4).
Batch tools help when you need ten lossy variants from one lossless master.
Using GetCompress
GetCompress runs lossy and lossless passes on your machine for JPEG, PNG, WebP, HEIC, video, GIF, and PDF. Choose quality presets for images and PDF, set target file size on video, preview before saving, and batch mixed folders. Masters stay untouched while delivery copies land beside them.
Use the free online image comparison slider to inspect a source and compressed export side by side before choosing the final quality setting.
Use lossless preview exports when stakeholders might crop or annotate; switch to lossy only for the final external send.
When a brand kit includes both SVG logos and PNG fallbacks, keep vectors lossless and compress raster fallbacks per destination.
Document which exports are lossy in handoff notes so downstream editors do not upscale a JPEG and expect RAW latitude.
Lossless archives cost disk; lossy delivery saves time. Both belong in a mature workflow.
- Optimize Images for Web on MacOptimize images for the web on Mac with a resize-first workflow, format comparisons, responsive variants, visual checks, and measured production delivery.
- Remove EXIF from Photos on MacRemove EXIF from photos on Mac with Preview export, sips strip flags, and GetCompress batch metadata removal. Share images without GPS and camera tags.
- Compress PNG on MacCompress PNG on Mac with Preview resize, oxipng lossless recompression, and GetCompress batch presets. Shrink screenshots without losing transparency.
- Compress JPG on MacCompress JPG on Mac with Preview quality slider, sips batch resize, and GetCompress presets. Shrink photos for email and uploads without visible artifacts.
Buy GetCompress now for local media compression with reusable presets and no media upload.