What does a histogram show?

A histogram shows the distribution of tonal values in an image. The left side represents shadows (dark tones), the middle represents midtones, and the right represents highlights (bright tones). The height at each point shows how many pixels have that brightness value.

What does clipping mean?

Clipping occurs when tones are pushed to pure black (0) or pure white (255) with no recoverable detail. Clipped shadows appear as solid black, clipped highlights as solid white. Once clipped, the detail is permanently lost and cannot be recovered in post-processing.

Should the histogram always be centred?

No. A "correct" histogram depends on the subject. A night scene should be shadow-heavy. A snow scene should be highlight-heavy. The key is that the histogram shape matches your creative intent and important detail is not clipped.

What is expose to the right (ETTR)?

ETTR is a digital exposure technique where you deliberately overexpose as much as possible without clipping highlights. This captures maximum data in the highlights where digital sensors are most efficient, then you reduce exposure in post-processing. It results in cleaner shadows with less noise.

Histogram Calculator — Exposure Distribution Analysis

Analyse your image exposure distribution and check for shadow and highlight clipping.

Shadows

Left third of histogram

Midtones

Centre of histogram

Highlights

Right third of histogram

Clipped Blacks

% of pixels at pure black

Clipped Whites

% of pixels at pure white

How We Calculate This

This calculator analyses the tonal distribution of your image based on the percentage of pixels in shadows, midtones, and highlights.

Enter your estimated percentages (they will be normalised to 100%) along with the percentage of clipped blacks and whites.

The calculator provides:

Distribution classification (balanced, low key, high key, flat)
Exposure assessment based on clipping levels
Suggested exposure adjustment in stops
Practical advice for improving the exposure

Frequently Asked Questions

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Last updated: February 2026

All calculations are estimates based on standard optical and photographic formulas. Results may vary with specific equipment.