LUT Cube Analyzer Free

RGB Channel Curves show how each colour channel is remapped from input (X axis, 0–100%) to output (Y axis, 0–100%). Curves above the identity diagonal lift tones; below it compress.

• Individual R / G / B panels isolate per-channel behaviour — useful for spotting colour casts in specific tonal zones
• All Channels Overlay superimposes all three curves on one canvas for a rapid contrast and white-balance read
• Hover anywhere on a curve to read the exact input → output value and the Δ delta from neutral for each channel
• Show Identity Diagonal — reference line where input equals output (no change); use it as a baseline to judge lift or compression
• Grid — toggles a 10×10 background grid for easier visual measurement
• IRE Markers — dashed lines at Rec.709 legal black (7.3%), midtone reference (64%), and legal white (92.1%); useful when grading for broadcast delivery
• Clip Zones — shaded bands at the top and bottom 2% where output values are likely to clip

Curves are derived from a neutral-axis sweep (R = G = B = input) — accurate for tonal mapping; full-gamut saturation behaviour is visible in the Scopes tab

The Preview tab renders the LUT output in a draggable split-view — original on the left, LUT-processed on the right. Use your own photo or one of the built-in synthetic test layers to evaluate the LUT's colour behaviour across the full tonal and hue range.

• Upload Image — load a JPEG, PNG, or WebP file (up to 20 MB); the LUT is applied entirely in-browser; the image is never transmitted or stored
• Hue Matrix — always-on synthetic base; hue sweeps the full 0–360° spectrum horizontally while saturation and brightness vary vertically; exposes hue rotation, colour shifts, and cross-channel contamination at a glance
• Grey Ramp (toggle) — 21 neutral steps from black to white; any colour cast or uneven tonal response is immediately visible on a neutral input
• Skin Tones (toggle) — 8 skin-tone patches from fair to dark; essential for portrait and documentary LUT evaluation
• Banding Test (toggle) — 64 fine steps each in the shadow (0–25%) and highlight (75–100%) zones; reveals posterisation and banding artefacts
• Split drag — drag the centre divider to compare any proportion of original vs processed output; current split percentage shown below

Synthetic layers are generated in sRGB / Rec.709. Wide-gamut or log-input LUTs should also be evaluated in the Scopes tab for full-range accuracy

Five professional scopes measure the LUT’s output mathematically. The Waveform, Vectorscope, Histogram, and CIE xy scopes use a 32³ test signal (32,768 RGB combinations) passed through the LUT via trilinear interpolation. The Saturation Response uses a denser HSV sweep (720,000 samples) for smooth, continuous chroma curves.

• Waveform — output level (0–100%) vs input value; use RGB Parade for per-channel lift/gain/gamma, Luma for a combined luminance trace, or Overlay to superimpose all three channels
• Vectorscope — chroma angle and saturation in Cb/Cr space; toggle 75% / 100% to scale the colour-bar target boxes; tight cluster near centre = low saturation, long radial axis = strong hue bias
• Histogram — value distribution per channel; switch between RGB and Luma modes; enable Log Scale to reveal detail in low-count bins
• CIE xy Chromaticity — output plotted on the 1931 CIE diagram; dashed triangle = sRGB gamut; red points = clipped out-of-range values
• Saturation Response — input chroma vs output chroma scatter; points above the diagonal = saturation boost, below = reduction; coloured by input hue to show which colour families are most affected

All scopes use a phosphor-density renderer (P50 median normalisation) — brighter areas indicate higher point density

LUT DNA automatically characterises the LUT mathematically — no manual reading required. Ten properties are measured and distilled into tags, metrics, a zone table, a character summary, and technical warnings.

• Tag pills — colour-coded labels auto-generated from the analysis (e.g. Warm, Lifted Shadows, Film Emulation, Strong LUT); give an instant fingerprint
• Radar chart — six axes scored 0–100: Strength, Contrast, Saturation, Warmth, Green Push, Smoothness
• Key metric tiles — six numerical readouts (Overall Strength, Contrast, Saturation, Colour Temp, Shadow Lift, Smoothness) with contextual colour coding
• Channel × Zone table — R/G/B average delta from identity across Shadows, Midtones, and Highlights; reveals selective grading and tonal imbalances
• LUT Character — plain-language summary generated from the metrics (e.g. "Warm, lifted shadows, gentle highlight roll-off. Best suited for outdoor footage.")
• Warnings — flags highlight clipping (>1.0), shadow crushing (<0.0), near-blocked shadows, and overly strong LUT strength with opacity advice

Export the full DNA report as a PNG for documentation or LUT library cataloguing

Compare loads a second .cube LUT and runs a full-gamut comparison — RGB tone curves, perceptual similarity scoring, per-channel delta, and a difference curve.

• Side-by-Side / Overlay Mode — view RGB curves on separate canvases or superimposed on a single canvas (LUT A solid, LUT B dashed) for direct visual comparison
• Hover tooltip — move over any curve canvas to inspect the input value, R/G/B output, and per-channel delta at that point
• Similarity Score — luma-weighted perceptual distance sampled at 33³ = 35,937 grid points; 100% = identical, lower = more divergent, with a plain-language qualifier (e.g. "Very similar — same base grade, different strength")
• Delta Analysis — R/G/B mean absolute error across the full 3D gamut, displayed as bars on a fixed 20% scale for cross-LUT comparability
• Difference Curve — A−B per channel along the neutral axis (R = G = B); auto-scaled to the actual peak delta so subtle differences remain visible
• Swap A⇔B — reverse the comparison direction without reloading files

Both LUTs must be standard .cube format. LUT A is set from the current LUT automatically; Overlay Mode and Swap activate once LUT B is loaded. Export the full comparison as PNG.