How-to

Check Your Drawing Against the Reference

You can stare at a finished drawing for an hour and still not see what is off. Laying it over the reference in the right mode makes the answer obvious in seconds, and tells you whether the problem is proportion, value or just the photograph.

  1. Photograph the drawing flat and evenly lit

    Shoot straight down, not at an angle, with light from both sides so the paper has no bright edge. A skewed photograph produces differences that look like drawing errors but come from the camera.

  2. Load both images and line them up

    Upload the drawing and the reference, then pan, scale, rotate and flip the top layer until the two agree. Take the time here. Every mode below reads the alignment you set, so a sloppy overlay makes every diagnosis wrong.

  3. Pick the mode that answers your question

    Each of the nine modes asks something different. Mirror reverses the drawing and exposes proportion drift your eye has stopped noticing. Squint blurs both panes down to value masses. Difference amplifies the gap between the two, so matches go pale and errors go dark until you switch the invert control off. Outline reduces your drawing to coloured edges laid over the untouched reference.

    The nine comparison modes: side by side, mirror, squint, difference, neon, multiply, screen, outline and splitThe nine comparison modes: side by side, mirror, squint, difference, neon, multiply, screen, outline and split, dark theme
    Nine modes, nine different questions about the same pair of images.

  4. Read the result honestly

    Difference mode shows every deviation, and not all of them are your fault. Uneven lighting, paper texture and the camera's white balance all register as differences. Look for systematic drift, a whole feature sitting too low or an axis leaning, rather than for an even scatter of noise.

  5. Mark what you found and carry on

    Drop reference lines on the eye line, the jaw or an axis of symmetry to fix what you saw, then send the composite straight into the grid maker if the next attempt needs a grid.

Compare your own drawing

Open the comparison workspace and load both images. It walks you through the first pass.

Open the comparison tool

Frequently asked questions

What does difference mode actually show?
The amplified gap between the two images at every pixel. Where they agree the result goes pale, where they diverge it goes dark. It measures pixels, not intent, so lighting and paper tone show up alongside real drawing errors.
My photo and the reference are different sizes. Does that matter?
No. Scale and rotate the top layer until the two line up. The tool does not require matching dimensions, only a matching alignment.
Why does mirror mode feel so brutal?
Because your eye adapts to a drawing while you work on it and stops registering the drift. Reversing it removes that familiarity. Atelier teachers have used a mirror for the same reason for centuries.
Should I compare before I finish?
Yes, ideally after the block-in. Proportion errors are cheap to fix at that stage and expensive once the shading is in.

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