How to split a long webtoon strip

A webtoon chapter is drawn as one tall image and read by scrolling. It rarely reaches you that way. A chapter usually comes as a set of tall files, cut at whatever height suited the site they came from. Those cuts were not made for translating: one can fall in the middle of a panel, or straight through a balloon.

Splitting the strip into pages, often called slicing, is the first job of a webtoon chapter, because everything after it goes page by page. An image editor is slow with an image 30,000 pixels tall, and some file formats cannot hold one at all. And a cut through a balloon breaks the sentence in it. Half sits at the bottom of one page and half at the top of the next, and neither half can be read, translated or lettered on its own.

Before you start

• Work from the files at their full width. Do not resize anything before you cut: scaling softens small lettering, and every page of a chapter should be the same width.
• Keep the files in the order they came in. Do not rename them until the strip is joined.
• Keep a copy of the originals, so a bad cut can be made again.

Any image editor with guides and a crop or slice tool will do.

Join the files back into one strip

Stack the files top to bottom in one tall canvas, in order, with no space between them and no overlap. A file boundary often lands in the middle of a panel or a balloon, and joining is the only way to get that balloon back in one piece.

Look at each join. The art should run across it with no doubled row and no missing one. If the whole chapter is too tall for your editor, join it in sections of a few files, and end each section at a clear gap.

Find the gaps

A webtoon is laid out with empty bands between its panels: plain background, white, black or a flat colour. That is where the artist expects a pause, and where a cut does no harm. Scroll down the strip and drop a guide in each one.

A gap runs the full width of the strip. The inside of a balloon or a caption box is plain too, but it has an outline on either side, and it is not a gap.

Cut only in a gap

Cut straight across, in the middle of the band, so both pages keep some of the empty space. Never cut through a balloon, a sound effect or a face.

• A deep band is a safer cut than a thin one.
• Narration lettered straight onto the background has thin plain bands between its lines. Keep all of its lines on one page.
• A sound effect often runs out of its panel into the gap. Cut above or below it.

Keep pages a sensible height

There is no one right height. Pick a target that your editor handles well and that holds a scene or two, then take the last gap before it. If the pages are going to a site or a tool with a height limit, stay under that limit.

The pages will come out uneven, and that is correct. An even split has to cut through panels. When one panel is taller than your target, leave it whole and let that page run long.

Name the pages so they sort

Number the pages with leading zeros: 001, 002, 003. Without them, some programs put page 10 before page 2, and the chapter reads out of order.

Check each cut edge

Open every page and look at its top and bottom edge. There should be no clipped letters, no piece of a balloon outline and no stray tail. Add up the page heights: the total should match the strip, so that no row was lost or saved twice.

Save the pages as PNG, or as JPEG at high quality. Each time a JPEG is saved again it loses a little detail, and fine lettering shows it first.

Common mistakes

• Cutting every page at the same height. An even split goes through panels.
• Cutting the files one by one without joining them first, so the cuts that came with them stay in.
• Taking the plain inside of a balloon, or the space between two lines of a caption, for a gap.
• Resizing before cutting, or ending up with pages of different widths.
• Page names that sort as 1, 10, 2.
• Saving the same JPEG again at every step.