Online Batch Image Gamma Adjustment Tool
Apply one gamma curve to up to 30 images. Set 0.1–5, generate previews, then download separate PNGs locally in your browser.
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What this tool actually does
Batch gamma adjustment accepts up to 30 selected images and applies one shared Gamma value to every loaded image. The numeric input ranges from 0.1 to 5 and defaults to 1.2; there is no per-image setting, automatic analysis or live effect preview.
Checkable behavior
For each red, green and blue byte x, output is 255*(x/255)^(1/gamma), with gamma clamped to 0.1-5 and output clamped to 0-255. Gamma 1 is the identity, values above 1 brighten midtones and values below 1 darken them. Alpha and dimensions stay unchanged.
Controls, output and limitations
Verified example for RGB(64,128,200): gamma 0.5 gives approximately RGB(16,64,157), gamma 1 gives RGB(64,128,200), gamma 2 gives approximately RGB(128,181,226), and gamma 5 gives approximately RGB(193,222,243) after byte rounding.
The curve is applied directly to gamma-encoded RGB channels. Integer rounding can merge nearby tones and does not estimate an image's transfer function, convert color profiles, work in linear light, adjust exposure stops or recover detail already clipped in the source.
Each input must have an image MIME type, be at most 25 MB and decode to no more than 24,000,000 pixels. The selected batch is capped at 100 MB and 40,000,000 decoded pixels; selecting more than 30 files rejects the whole batch.
Generate creates one browser preview per loaded image. Every result is encoded as PNG and named from the source base name plus -gamma.png. Download all starts separate downloads about 180 ms apart; it does not create a ZIP, retain source format or preserve metadata.
Processing is local in the browser. Use gamma 1 as a neutral reference and change it gradually because one shared curve may suit one image but flatten or darken another. This is not RAW development, monitor calibration, HDR tone mapping or AI correction; keep the originals.
The curve maps 0 to 0 and 255 to 255; it never exceeds the byte range mathematically. Extreme settings can merge distinct tones after integer rounding. An empty field uses gamma 0.1, not the initial 1.2. Out-of-range values are clamped to 0.1–5 without rewriting the field. Each Generate starts from the loaded source; use 1 to restore decoded RGB.
Per image: ≤25 MiB and ≤24,000,000 pixels. Per batch: ≤100 MiB and ≤40,000,000 pixels. Selecting over 30 files or any invalid image rejects the whole batch.
Processing takes place locally in your browser.