EditHistogram

Histogram

Your eyes lie to you. Screen brightness, True Tone, and the light in the room all change how a photo looks, which makes it genuinely hard to know when you've hit pure black or pure white — or whether a neutral wall has picked up a color cast. The histogram doesn't lie. It's a diagram of how your pixels are distributed from black on the left to white on the right, plotted for the red, green, and blue channels, and it turns "this looks about right" into something you can actually verify.

To show it, tap the ••• action menu while viewing a photo and choose Show Histogram (or enable it in Settings); swipe it off to the right to hide it. Keep it up whenever you're making exposure- or color-critical decisions.

Darkroom histogram showing dark, balanced, and bright exposures across three devices
A dark photo piles up on the left, a bright one on the right, and most photos sit center-weighted. There's no single correct shape.

When it comes to histogram shapes: don't chase a "perfect" centered histogram. Plenty of beautiful images are deliberately low-key or high-key. The histogram is guidance, not a target.

Use the full tonal range

Phones try to expose for the whole tonal range, but they struggle with glare, backlight, or shooting through glass — and the result often looks flat. The histogram makes the fix obvious: if the graph doesn't reach the right edge, you have no true whites; if it stops short on the left, no true blacks. Stretch your Whites and Blacks until the data fills the range and the image gains richness and depth. Many professionals do exactly this as their first move.

A flat photo lacking true white and black, and the same photo corrected to use the full tonal range
The histogram on the left never reaches the edges; stretching whites and blacks uses the full range for a richer result.

Spot and fix color casts

The color channels reveal problems your eye glosses over. Here's the key idea: where red, green, and blue overlap, you get neutral gray. So if a region should be gray but the channels are pulling apart, you have a cast — and the histogram tells you which way to correct. Align the channels with Tint and Temperature (or Curves) and the cast disappears.

A photo with a green-blue tint and the corrected version, with histograms
Shot through tinted glass, this image skews green-blue in the highlights; aligning the channels neutralizes the cast.

Watch for clipping

Clipping is data pushed out of range — highlights blown to featureless white, or shadows crushed to pure black, with detail lost for good. Tools like Whites/Blacks, Curves, and Vignette make it easy to clip without noticing. When the histogram is visible, Darkroom calls it out with plain-language indicators and even marks the offending pixels right on your photo — clipped whites in red, clipped blacks in blue. Decide whether that clipping is an intentional style choice or a mistake, and re-check after any big tonal move or finishing effect.

One related gotcha: stretching the range too aggressively causes posterization — banding where you'd expect a smooth gradient, most visible in blue skies. You'll spot it as jagged steps in the histogram, and a little Grain helps disguise it.

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