Online Batch Image Histogram Tool

What this tool actually does

Batch image histogram accepts up to 30 selected images and has no adjustable processing controls. Generate analyzes each loaded image independently and produces a histogram graphic rather than a modified copy of the source image.

Checkable behavior

The browser counts exact 8-bit red, green and blue channel values in three separate arrays of 256 bins. Pixels with alpha zero are ignored so invisible stored RGB does not create misleading peaks; pixels with any nonzero alpha are counted once without alpha weighting.

Controls, output and limitations

Each result is a fixed 760-by-380 white canvas. Red, green and blue frequency lines are drawn at 72% opacity over the same plot, scaled to the largest channel-bin count in that image. The horizontal endpoints are labeled 0 and 255; there is no logarithmic scale, grid, numeric table or CSV export.

Verified example: visible pixels RGB(10,20,30) and RGB(10,40,50) create red bin 10 with count 2 and green bins 20 and 40 with count 1 each. A fully transparent RGB(200,210,220) pixel contributes no counts. A fully transparent image produces a safe empty baseline rather than invalid coordinates.

This is an RGB channel histogram, not a luminance histogram, color palette, exposure score, clipping diagnosis or automatic correction. Peaks show frequency, not pixel positions, and overlapping translucent lines can visually mix where channels share bins.

Each input must have an image MIME type, be at most 25 MiB and decode to no more than 24,000,000 pixels. The selected batch is capped at 100 MiB and 40,000,000 decoded pixels; selecting more than 30 files rejects the entire batch.

Every graph is encoded as PNG and named from the source base name plus -histogram.png. Download all starts separate downloads about 180 ms apart; it does not create a ZIP or export raw bin data. Processing is local in the browser and does not preserve source metadata in the graph.