Fix or iterate on existing art

Editing someone's work has a failure mode that drawing from scratch does not: breaking something that was already correct. The whole procedure is built around not doing that.

Procedure

1. Understand what is there before changing it

preflight
sprite_info
look op="preview"

For a targeted edit, also look op="ascii" on the region. You cannot edit pixels precisely from a description.

Never assume layer names, frame counts or the palette. Drawing into the wrong layer is the most common way an agent damages someone's file. When two groups hold same-named layers (left/arm, right/arm), a bare name is refused — pass the group path rather than renaming the user's layers.

2. Say what you are about to change

For anything beyond a small touch-up, state the plan in one line and let the user stop you. Especially before: changing the palette, resizing the canvas, merging layers, or editing a layer you did not create.

3. Scope the edit as tightly as you can

• A selection limits draw, recolor and transform to one area.
• A layer target keeps you out of everything else.
• A region on recolor avoids touching the whole cel.

Scoping is cheaper than repairing.

4. Make the change in one call

One draw with all its ops, one recolor. That is one Ctrl+Z for the user if they dislike it. Use label to describe the intent — it becomes their undo entry.

For a pixel-level fix, edit the text, not coordinates: look op="ascii" layer=… rulers=false region=… gives bare rows, the legend and origin; change the wrong cells and send the same rows back as one draw kind grid at that origin. Only that rectangle is touched, and its transparent cells erase — pass transparent:"skip" when you mean to add pixels without clearing any. Glyphs are palette indices, so pieces read separately share one legend: merge their legends when rows from one piece land in another. Only glyphs listed in offPalette (colours outside the palette) can change between reads.

5. Verify what actually changed

look op="diff" fromFrame=… toFrame=…

for animation work, or look op="ascii" on the region for a static edit. A preview shows you the result; a diff shows you the change, including the parts you did not intend. The diff's changedBounds is the quick test: if you edited the hand and the box spans the whole sprite, something else moved.

6. Validate and report

validate

Report what changed and what you deliberately left alone.

Interpreting vague requests

Reflect your reading back before acting on it. "More detail" on a 16×16 sprite usually means the sprite needs to be bigger, and that is worth one question.

What not to do

• Do not redraw a sprite from scratch because it is easier than editing it, unless the user asked for that.
• Do not "improve" things nobody mentioned.
• Do not widen the palette to fit a colour you chose. Say the palette lacks it.
• Do not flatten, resize or re-index without being asked.

Related

aseprite:review, rules://00-core-principles, rules://92-generated-art-tells for what makes art read as machine-made, and the subject file for the part you are fixing (skill://studio, Subject rules) — "fix the hands" starts at rules://34-hands-and-feet.