How JPG Compression Works
JPG compression is the reason photos can be small enough to upload, email, and post online. It reduces file size by removing detail the eye is less likely to notice. Used carefully, it makes images lighter. Used too aggressively, it creates blocky edges, color bands, and blurry texture.
Quick answer
JPG compression makes photos smaller by discarding some image detail and simplifying color information. Higher quality settings keep more detail but create larger files. Lower settings shrink files more, but can create visible artifacts.
Quality and artifacts
A quality setting around 80 to 90 often works well for everyday photos. Very low settings can create square blocks around details or rough edges around text.
Practical example
A vacation photo can usually be compressed heavily without obvious issues. A screenshot of a spreadsheet may look bad as JPG because text and grid lines expose artifacts quickly.
Step-by-step instructions
- Start from the original image when possible.
- Choose a balanced quality setting.
- Preview the image at the size people will view it.
- Use Compress Image or PNG to JPG depending on the source.
Common mistakes
- Compressing the same JPG again and again.
- Using JPG for text-heavy screenshots.
- Choosing the smallest file without checking visible quality.
Troubleshooting
- The photo looks blocky.
- Use a higher quality setting or start from the original file.
- Text looks fuzzy.
- Use PNG for screenshots or export at higher resolution before compressing.
FAQ
Is 100 percent JPG quality best?
Not always. It creates larger files and may not look noticeably better than a balanced setting.
Does JPG support transparency?
No. Use PNG or WebP if transparency is required.
Compress a JPG or PNG
Reduce image size with a quality setting that still looks good.
Open Compress Image