Image / Effects
Black and White Photo — Local Browser Tool
Convert a colour photo to greyscale using weighted RGB, average RGB or one channel, with contrast, brightness and sepia controls.
Black and White Photo — Local Browser Tool: Start with Rec. 709 weighted RGB for a familiar black-and-white appearance, or compare average RGB and the red, green and blue channels. The weighted option uses 0.2126 red, 0.7152 green and 0.0722 blue on the stored RGB values. It is a practical greyscale conversion, not a linear-light luminance measurement. Channel options can separate subjects with different colours, such as red lettering against green foliage. Contrast expands or compresses values around middle grey; brightness adds or subtracts an offset. Strong settings can clip shadows to black and highlights to white. Sepia adds a warm tint after greyscale and tonal adjustments. The preview shows the final colour effect and keeps the original transparency. Export as PNG and use the export scale control for the saved dimensions. Files smaller than 50 MB, with each dimension at most 8192 pixels and a total of at most 40 million pixels, are accepted. Runs 100% locally in your browser with zero server file uploads.
- Category
- Image tools
- Runs
- In your browser
- Cost
- Free · no sign-up
- Availability
- Ready to use
Runs entirely in your browser
Click, drag and drop, or paste · stays on this device
PNG, JPG or WebP · up to 50 MB and 40 million pixels · processed on this device
Greyscale weights
ITU-R BT.709 (https://www.itu.int/rec/R-REC-BT.709) specifies the familiar red, green and blue weights. Here they are applied directly to decoded RGB values; colour-managed print workflows may need a different conversion.
Local image export
PNG output keeps transparency and the image dimensions shown beside the download. Export scale changes the saved dimensions; preview controls remain in original image pixels. The HTML canvas specification (https://html.spec.whatwg.org/multipage/canvas.html) describes browser image rendering and export.
How to use it
- Choose a file in the input format shown.
- Adjust the available output controls.
- Create the result, check its preview and download it.
Privacy & limitations
Your file is processed on this device. No image, video or audio is uploaded.
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Frequently asked questions
Which greyscale method should I choose?
Weighted RGB usually gives a useful starting point because green contributes more than blue. Average RGB treats the channels equally. A single channel can make some coloured objects lighter or darker; compare the preview before downloading.
Is the sepia result still black and white?
Sepia adds brown and gold tones to the greyscale image. Turn it off for neutral grey pixels. It is a stylised preset, not a simulation of a particular film or print process.
Does export scale change contrast?
No. Contrast and brightness are applied before resizing the PNG. A 50% export has half the width and height; increasing size cannot add detail missing from the original.
Free tool · runs in your browser · no account required