Key takeaways
Scan at 600 dpi in grayscale. Clip Studio's own guide recommends 600 dpi or higher for monochrome work and 350 dpi for color drafts.
Make the paper transparent with a tool that turns white into see-through pixels, such as Convert brightness to opacity in Clip Studio Paint or Color to Alpha in Krita and GIMP. This keeps thin lines better than a hard black-and-white threshold.
Use a threshold only on a high-resolution scan, or lines will turn jagged.
Phone scans work if the light is even and the camera is parallel to the page, but turn off any document filter that flattens light pencil.
Vectorize last, and only if you need to resize the art without limits.
What you need
A drawing on white or light paper, ideally with dark, solid lines.
A flatbed scanner, or a phone with a scanning app.
An image editor such as Clip Studio Paint, Krita, GIMP, Photoshop or Procreate.
Optional: Illustrator, Inkscape or Vectorizer.AI for vectors.
Step 1: Scan at a high resolution
Put the page flat on the glass, close the lid and scan in grayscale at 600 dpi. Clip Studio's guide for scanning drafts recommends 600 dpi or higher for monochrome work and 350 dpi for a color draft, and warns that too low a resolution won't convert properly to a monochrome draft. Epson's guidance adds that you should raise the resolution by the same factor as any enlargement, so a small sketch you plan to print at double size should be scanned at double the dpi.
Scanner makers don't publish advice on bitmap versus grayscale for line art. Grayscale is the safer choice, because a 1-bit scan fixes the scanner's own black-and-white cutoff before you can adjust it. Save the file as a PNG or a TIFF, not a JPEG, so the edges don't pick up compression artifacts.
Step 2: Or photograph it with your phone
A phone scan is fine for sketchbook pages. Use even daylight or a lamp on each side so nothing casts a shadow across the page, hold the phone directly above the paper and keep the page flat.
On an iPhone, open Notes, tap the attachment button, choose Scan Documents, drag the corners to fit the page and tap Keep Scan. The Files app has the same Scan Documents option.
Most scanning apps detect the page edges and flatten the perspective when you drag the corners, so set them carefully.
For pencil drawings, choose the plain color or original option and skip any black-and-white document filter. Those filters raise contrast and can erase the lightest pencil strokes.
Step 3: Straighten and crop
Crop away the scanner bed or the table, and rotate the page until the drawing's horizontal lines are level. In Photoshop, GIMP and Krita, use the crop tool and a rotation handle. Scanning apps usually correct perspective for you when you drag the corners to the page edge. Do this before any cleanup so that later steps work on the final crop.
Step 4: Turn the paper white and the lines dark
Scans come in with gray paper and gray lines, so push the white point and black point together.
Photoshop: Choose Layer > New Adjustment Layer > Levels, or Image > Adjustments > Levels if you don't need to keep the original. Drag the white input slider left until the paper turns white and the black slider right until the lines are dark, stopping before the thinnest strokes break up.
GIMP: Choose Colors > Levels and drag the same two sliders.
Krita: Open the Levels filter and use its histogram the same way.
Use an adjustment layer where you can, because you'll be able to change the settings later.
Step 5: Make the paper transparent
The goal is a layer of lines with nothing behind them, so you can put color underneath.
Clip Studio Paint: Select the layer and choose Edit > Convert brightness to opacity. White becomes transparent, grays close to white become faint and dark areas stay solid. The command doesn't work on an Image material layer, such as one from File > Import > Image, so rasterize the layer first from the Layer menu. If you have a PRO or EX license, you can also open the Layer Property palette, set Expression color to Monochrome and adjust the Color threshold.
Krita: Choose the Color to Alpha filter and leave white as the color. The manual says it's useful for separating line art from a white background, and a Threshold setting controls how much of the nearby tone is removed.
GIMP: Choose Colors > Color to Alpha. If the layer has no alpha channel, add one first with Layer > Transparency > Add Alpha Channel.
Photoshop: Choose Select > Color Range, pick Sampled Colors and click a dark line with the eyedropper. Raise the Fuzziness slider until the thinnest lines are selected, then press Ctrl+J (Cmd+J on Mac) to copy the lines onto their own layer and hide the original.
Procreate: There's no scanning feature, so scan with Notes or Files and bring the image in with Actions > Add > Insert a photo. Set the layer's blend mode to Multiply, which makes white disappear against the layers below.
Step 6: Clean up specks and smudges
Zoom to 100% and look over the whole page. Erase stray marks by hand where you can. For a lot of fine dust, Photoshop has Filter > Noise > Dust & Scratches. Start the Radius at 1 or 2 pixels, since a bigger radius blurs your lines, and raise the Threshold to protect detail. In GIMP, Krita and Clip Studio Paint you'll mostly use the eraser on a copy of the layer.
If you need solid black lines with no gray at all, apply a threshold after the cleanup. GIMP has Colors > Threshold and Krita has a Threshold filter, both based on brightness. In Clip Studio Paint, Expression color > Monochrome does the same job. A threshold works best on a 600 dpi scan, because the edges have enough pixels to stay smooth.
Step 7: Save the lines on a transparent background
Hide any other layers and export the line layer as a PNG with transparency on. To color it later, use alpha lock so paint stays inside the lines. In Procreate, tap a layer to open Layer Options and turn on Alpha Lock, which keeps new paint within the existing artwork.
Step 8: Convert to vectors if you need to scale
Vectors let you enlarge art to any size without softening. Only trace once the raster file is clean.
Illustrator: Open the Image Trace panel and start from the Black and White preset. Adjust the Threshold slider and check Ignore White so you get black shapes only.
Inkscape: Choose Path > Trace Bitmap (Shift+Alt+B) and set the Brightness cutoff threshold between 0.0 and 1.0.
Vectorizer.AI: Uploading and previewing are free, and you pay $9.99 a month on its web plan to download.
Expect to adjust the threshold several times. A trace that's too light loses thin strokes and one that's too dark fills in small gaps.
Common mistakes
Scanning too low. Thin lines break up when you threshold a 150 dpi scan, so scan at 600 dpi.
Thresholding too early. A hard cutoff throws away the soft edges of ink, so use Convert brightness to opacity or Color to Alpha on thin work.
Using a document filter. Scanner apps often increase contrast automatically and can erase light pencil.
Smoothing too much. A strong blur or a large Dust & Scratches radius removes specks and fine detail together.
Leaving the file huge. A 600 dpi scan can be very large, so reduce the size after you've finished the cleanup and keep the original untouched.
Handing the job to an AI redraw tool. Generative tools redraw lines instead of preserving yours, so use threshold and alpha methods when your own linework matters.
Frequently asked questions
What dpi should I scan line art at?
600 dpi in grayscale is a good default. Clip Studio's guide recommends 600 dpi or higher for monochrome work and 350 dpi for color drafts. Scan higher if you'll enlarge the art.
How do I remove the white background from a scanned drawing?
Use a tool that converts white to transparency. In Clip Studio Paint it's Edit > Convert brightness to opacity, and in Krita and GIMP it's Color to Alpha. In Photoshop, use Select > Color Range to pick the lines and copy them to a new layer.
Can I scan line art with my phone?
Yes. Use even light, hold the phone parallel to the page and keep the page flat. Skip any black-and-white filter on pencil drawings.
How do I remove blue pencil from a scan?
Blue pencil often fades when you scan in grayscale and raise the contrast, because light blue turns pale gray. If it's still there, lower the blue slider in a Black & White adjustment before you set the levels.
How do I turn a scanned drawing into a vector?
Clean the scan first, then trace it. In Illustrator, use Image Trace with the Black and White preset and Ignore White checked. In Inkscape, use Path > Trace Bitmap.