How do I batch-convert color photos to black and white?

Choose the black and white preset, which sets grayscale to 100% and raises contrast to 110%. Grayscale weights red, green and blue by 0.2126, 0.7152 and 0.0722, matching perceived brightness more closely than a simple average of the three channels. Up to 30 photos can be processed together, and each one can be downloaded separately or in a single ZIP.

Are these settings the same as CSS filters?

The formulas are the same: brightness 150% matches brightness(150%), contrast pivots around 127.5, and saturation, hue, grayscale and sepia use the specification's matrices. Compared one by one against Chrome's CSS filters, results differ by no more than 2 color levels. When several settings are combined, this page uses a fixed order, which may differ from the order in your CSS.

What sharpening strength works best?

For photos, 20%–40% usually works well. Sharpening is a 3×3 convolution with a center weight of 1 + 4a and −a on each of the four neighbors, so at 100% strength visible halos appear along edges. Blur ranges from 0 to 20 pixels, and when both are set, blur is applied first and sharpening last, after all of the color adjustments.

Image adjust & filters

Batch-adjust brightness, contrast, saturation and hue, and apply grayscale, vintage, blur or sharpen effects

Computed in your browser

Drop images, pick a preset or drag the sliders, and results update automatically; confirm in the comparison preview, then download.

Choose or drop images You can also paste an image from the clipboard. Images are processed in this browser and never uploaded. JPG, PNG, WebP, AVIF, BMP and GIF; up to 30 files, 50 MB each.

Preset

Brightness 100%

Contrast 100%

Saturation 100%

Hue 0°

Grayscale 0%

Sepia 0%

Invert 0%

Blur 0px

Sharpen 0%

Output format

Quality 92

Example

Input

sample.png (generated, 1200×800) · Vintage preset: sepia 60%, contrast 110%, saturation 80%, brightness 105%

Example result

sample-adjusted.png · 1200×800, warmer with slightly more contrast; drag the comparison preview to inspect

These values mean the same as CSS filter: sepia(60%) contrast(110%) saturate(80%) brightness(105%), although this page applies them in a fixed order.

Technical details & limits

Color adjustments use the formulas from the CSS Filter Effects specification per pixel: brightness is c × b, contrast scales around 127.5, saturation, hue, grayscale (0.2126/0.7152/0.0722 weights) and sepia use the specification's 3×3 matrices, and invert is c × (1 − i) + (255 − c) × i. The order is fixed: blur → brightness → contrast → saturation → hue → grayscale → sepia → invert → sharpen. Blur uses the browser's Gaussian blur and is disabled where unsupported; sharpening is a 3×3 unsharp convolution. Results are re-encoded without metadata.

About this tool

Batch-adjust images locally in your browser with 9 controls: brightness, contrast, saturation, hue, grayscale, sepia, invert, blur and sharpen, plus presets for black and white, vintage, vivid, faded and inverted looks. Results recalculate as you drag, with a comparison preview, single downloads or a ZIP, and output as the original format, JPEG, PNG or WebP. Images are not uploaded.

How to use

Drop, choose or paste images, up to 30 at a time.
Pick a preset or drag the sliders; results update automatically, and Reset all returns to the original values.
Check the comparison preview, then download single files or a ZIP.

Input & output

Input: JPEG, PNG, WebP, AVIF, BMP and GIF (first frame); up to 30 files, 50 MB each.
Output: Adjusted JPEG, PNG or WebP files, downloadable singly or as a ZIP.
Limits: Settings apply to the whole image; no local edits, curves, levels or RAW files; metadata and animation are not kept.

Notes

Each change is recalculated from the original, so repeated adjustments do not accumulate loss. Sharpening large images is slower; resize first if needed.

FAQ

How do I batch-convert color photos to black and white?: Choose the black and white preset, which sets grayscale to 100% and raises contrast to 110%. Grayscale weights red, green and blue by 0.2126, 0.7152 and 0.0722, matching perceived brightness more closely than a simple average of the three channels. Up to 30 photos can be processed together, and each one can be downloaded separately or in a single ZIP.
Are these settings the same as CSS filters?: The formulas are the same: brightness 150% matches brightness(150%), contrast pivots around 127.5, and saturation, hue, grayscale and sepia use the specification's matrices. Compared one by one against Chrome's CSS filters, results differ by no more than 2 color levels. When several settings are combined, this page uses a fixed order, which may differ from the order in your CSS.
What sharpening strength works best?: For photos, 20%–40% usually works well. Sharpening is a 3×3 convolution with a center weight of 1 + 4a and −a on each of the four neighbors, so at 100% strength visible halos appear along edges. Blur ranges from 0 to 20 pixels, and when both are set, blur is applied first and sharpening last, after all of the color adjustments.

Related tools

Image adjust & filters · Batch-adjust brightness, contrast, saturation and hue, and apply grayscale, vintage, blur or sharpen effects — Image adjust & filters — Tool illustration · dayeku.com

Comparison