Sprite Slicer

This is what you are aiming at: the body holds still and the legs and head carry the movement. Match the speed slider to it, then compare against your own rows below — if yours changes shape everywhere at once, that is the art, not the cut.

What the sheet needs

• A flat background the creature never uses — magenta is the convention. It is read from the corners, so it does not need to be exactly #FF00FF.
• Clear gaps between frames and between rows. Frames that touch are found as one.
• The same number of frames in every row.
• Its own dark outline, which pixel art normally has. Close outline darkens the edge only where that outline has gone missing, so the rim runs all the way round without being thickened. Outline gaps sets how light a pixel has to be to count as a gap.
• Specks — the smallest island of pixels to keep. Keying leaves crumbs adrift from the creature, outside its outline, and they wink in and out as the frames change. Raise it to sweep harder; drop it to 0 if something genuinely detached, like a trailing wisp, is disappearing.

Everything else is measured: where the rows sit, where each frame's edges are, and where the creature's body is so the frames line up instead of shuffling. If a row cannot be cut, it says which one and why.

When the measuring gets it wrong

• Remove — the background colour, read off the corners. Turn Auto off and pick it by hand when a sheet has something in its corners, or when the background is not quite flat.
• Keying — how far from that colour still counts as background. Push it up if a haze of background survives around the creature; pull it down if the creature is being eaten.
• Edge — how many pixels to shave off all the way round. Between the background and the creature lies the band where the art was blended into the key, and no colour test separates it. One pixel usually takes it. Raise it if the edge looks dirty, drop it to 0 if thin details like a wisp of wind are disappearing.
• Keep drawing — normally the frames are scaled down to the size the game draws them and snapped to a small palette, which is what gives them hard edges and flat colour. Turn this on and the drawing comes through as it was made instead: full size, soft edges, every colour. Everything after the scaling — height, colours, contrast and the outline — belongs to pixelating and is ignored while it is on.
• Contrast — spreads the shading apart. Generated art tends to sit in one band of mid-tones where hand-drawn pixel art runs from near-white to near-black.