Main Features
- Supports local batch image upload and folder import for unified contrast tuning.
- Supports contrast range from -100 to 100 with linked slider and text input.
- Supports side-by-side preview of source and processed results.
- Supports processing current image or all queued images.
- Supports single and bulk download, with JPG output format.
How To Use
- Click Select Images or Select Folder, or drag images into the upload area.
- Set the contrast value and review the factor hint.
- Click Process Current or Process All to generate outputs.
- Download current output or download all processed results.
Processing Logic
The tool uses the classic contrast formula:
factor = 259 * (contrast + 255) / (255 * (259 - contrast))
Then applies this per channel:
newValue = (value - 128) * factor + 128
This increases or reduces light-dark separation without changing image dimensions.
Use Cases
- Batch contrast enhancement for ecommerce product image consistency.
- Fast highlight and shadow separation in photo post-processing.
- Visual strengthening and readability optimization for social media assets.
- Privacy-friendly local processing workflow for operations image materials.
Notes
- After changing contrast values, previous outputs must be processed again.
- Output format is fixed to JPG, and transparent areas are flattened to white.
- For large queues, process in batches to reduce browser memory pressure.
- All processing runs locally in your browser, with no server upload.
FAQ
Why do old results not change after I modify contrast?
Existing outputs were generated with previous settings, so you need a new processing pass.
Will contrast adjustment resize my images?
No. The tool only rewrites pixel color values and keeps original dimensions.
Can I batch process mixed image formats?
Yes. Common formats can be imported together and are exported as JPG outputs.