Free Value-to-Pencil Grade Mapper
Every pencil grade owns a band of the value scale: 2H lives in the lights, 8B in the deep shadows. This tool posterizes your reference into flat value regions and labels each one with the grade that can actually produce it. Print the swatch sheet, fill it with your own pencils and photograph it: the table reads your real values automatically. Then print the map, or numbered outlines to transfer. Exports PNG and PDF. Free, with no sign-up, and your picture never leaves your device.
Drop an image here, or paste from clipboard
Your image stays on your device. Nothing is uploaded.
JPG, PNG, WebP, GIF, AVIF or BMP
Swatch sheet calibration.Print a sheet with a box per grade, fill it, photograph it, and every value is read into the table.
Transfer outlines.Numbered zone outlines on white, one number per grade, to trace onto your paper before shading.
Saved tables.Keep up to 20 named, calibrated tables in this browser: one per paper or pencil set.
Three medium presets.Graphite, Charcoal and Coloured pencil starting tables, each fully editable from 2 to 12 rows.
- Free
- No sign-up
- Runs in your browser: your image never leaves your device
What is a pencil grade value map?
A pencil grade value map is a reference image posterized into flat value regions, each labeled with the pencil grade or charcoal that makes that value. This mapper assigns every pixel to the nearest row of a table you calibrate from a printed swatch sheet, and exports the map or numbered transfer outlines as PNG or PDF.
How to use the Value-to-Pencil Grade Mapper
The tool takes 6 steps, all on your device.
Drop in your reference photo (or tap a sample): the image is posterized into flat gray regions, one per grade row.
Pick a Medium preset: Graphite gives seven grades from paper-white to 8B, Charcoal five from paper to compressed charcoal, and Coloured pencil six rows to rename after the pencils you own.
Under Calibrate with the swatch sheet, choose A4 or Letter and Download the swatch sheet. Print it at 100%, fill each labelled box with firm, even tone from that grade, and photograph the whole sheet with its four corner marks in view.
Add that photo under Photo of the filled sheet. The marks are found, the perspective is undone and every box's value is written into the Grade mapping table; boxes you left empty keep their old value.
Name the calibrated table and Save in this browser, so the next session can Load it instead of swatching again.
Under View, switch between Grade map and Transfer outlines, then Export PNG, or Export printable PDF for the image and its legend on one page.
What the Value-to-Pencil Grade Mapper does
The Value-to-Pencil Grade Mapper assigns one grade to each value region, from swatches read in a photo, and draws outlines for transfer.
One grade per value region
The Value-to-Pencil Grade Mapper posterizes a reference into flat grays, one per table row, and names the grade that makes each one. Among the value and tone tools for artists, it is the one that turns values into the pencils you pick up.
Read from a photo, not guessed
The swatch sheet carries 4 corner marks. The mapper finds them in your photo, undoes the tilt and measures each box against the bare paper, so a dim or warm light cancels out.
Nearest-row matching
The mapper measures each pixel's OKLab lightness and assigns it to the row with the closest value. Rows always sort lightest first, whatever order you type them in.
Outlines you can transfer
Transfer outlines draws only the grade zones' borders, numbered where they fit. Row 1 is the lightest, so the legend is the key.
Full-resolution exports
Exports rerun the map or outlines on the full-resolution photo, not the 1,600-pixel preview. The legend lists each grade's L value and share of the image.
Private by construction
The mapper reads your reference and your sheet photo and builds every export in your browser; no image is ever uploaded. Saved tables stay in this browser's storage and nowhere else.
Artists who choose pencils by value
Draughtsmen, art students, art teachers and coloured pencil artists choose pencils by value with the map.
Draughtsmen
Draughtsmen can calibrate a table for each paper they use, save it, and print the map beside the drawing board.
Art students
Art students can switch one reference between the Graphite and Charcoal presets to see how each medium splits the same values.
Art teachers
Art teachers can hand out the swatch sheet as a first exercise, then the numbered outlines as the drawing that follows it.
Coloured pencil artists
Coloured pencil artists can rename the rows after their own pencils and sort a colourful set purely by how light each one draws.
Why map values to pencil grades at all?
Values are mapped to pencil grades because a reference photo holds hundreds of grays and a pencil case holds a handful of grades. Deciding in advance where information goes beats finding out mid-shadow. A grade map turns the continuum into one question per shape: which pencil do I pick up?
Reading the posterized map
Each flat region on the map is one row of the table. Where the photo fades gradually, the map draws a hard boundary where the value enters the next grade's territory; there your drawing changes pencil, pressure or hatch density. Flick between photo and map in the compare views: shapes that survive are the masses to keep, and vanished detail belongs to the rendering stage.
For fewer, hand-placed value breaks instead of grade rows, the value study maker posterizes the same photo with thresholds you drag.
Calibrating with the swatch sheet
The swatch sheet prints a labelled box for every row except the paper, with a solid square in each corner.
Fill each box edge to edge with the firmest even tone you really use from that grade, then photograph the sheet flat, in even daylight, with all four squares in frame. Each box is sampled inside its edges, compared with the bare paper in the margins and converted to the table's L scale, so a yellow lamp reads the same as a window. Empty boxes are skipped, so swatch only the grades you own. If the marks can't be found, nothing changes; Or sample values by hand still lets you click swatches on any photo.
Editing the table to match your hand
Rename rows to what you own and remove grades you never use; a table holds 2 to 12 rows. Add grade fills the widest gap and keeps every calibrated value. Once a table is right, name it and save it; saving under an existing name replaces that table, and loading one restores its medium.
When a photo's darks go deeper than your pencils can, the value range compressor first re-keys the reference into the span graphite or charcoal reaches.
Transfer outlines: a line drawing sorted by grade
Switch View to Transfer outlines and the zones become dark borders on white, each numbered where it is wide enough; thin slivers stay unnumbered and specks merge into their neighbours. Print at the size of your drawing, transfer the lines lightly, then shade each zone with the grade the legend gives its number.
Further reading
The page below goes further into the ideas the Value-to-Pencil Grade Mapper works with, and opens on the site named beside it.
- Value structure, materials and the drawing curriculum (ArtisticMasterclass.com)
Tips from a working artist
From Sujith Puthran, artist and founder: what I actually do at the easel.
Swatch on the paper you will draw on (the same pencil reads differently on smooth Bristol than on rough cartridge) and save one table per paper.
Fill the swatch boxes with the pressure you really draw with, not your hardest; the map can only promise what your hand repeats.
The grade covering most of the image in the legend is the value to establish first.
Charcoal users: give the lightest rows to vine or willow and reserve compressed for one or two dark rows. It is nearly impossible to lift back out.
Why your picture stays on your device
The Pencil Map is a program your browser downloads and runs by itself. When you choose a picture, the browser reads it from your files and does the work on your own phone or computer; no copy is sent to this site or to anyone else, and what you export is saved straight from the browser. That is why there is nothing to upload and nothing to sign up for. The privacy page says what the site does collect.
Questions about the Value-to-Pencil Grade Mapper
The 6 questions below cover how a grade is chosen and what L means, then your own pencils, charcoal and the saved table.
The numbers
How does the mapper choose a grade for each pixel?
The mapper chooses a grade for each pixel by sending the pixel to the table row whose value is closest to its OKLab lightness. The region then takes that row's flat gray and its grade label.
What does the L value number mean?
The L value number is OKLab lightness on a 0–100 scale, where 0 is ideal black and 100 is ideal white, and equal steps look roughly even to the eye. It is not the artist's 1–10 value scale. The Value Range Compressor uses the same L numbers, so values measured here carry over.
How accurate is reading the swatch sheet from a photo?
Reading the swatch sheet from a photo is accurate to within 2 L in our test: on a synthetic sheet photographed tilted, dim and under warm light, every grade read back within 2 L of its true value. Real photos add glare, so shoot in even daylight without a flash and correct any row that disagrees with the sheet.
Your own pencils
My pencils don't match the preset values. Is the tool wrong?
No, the tool is not wrong when your pencils don't match the preset values: the presets are estimates for medium pressure on white paper, and your hand, pencils and paper differ. Fill the swatch sheet and add a photo of it to replace the estimates with measurements.
Can I use this for charcoal on toned paper?
Yes, you can use this for charcoal on toned paper: make the lightest row your paper's tone and add a white-chalk row above it; the map then spreads the reference across the range you can reach.
Does the mapper save my edited table?
Only when you ask: the mapper saves your edited table through Save in this browser, which keeps up to 20 named tables in this browser's storage, never on a server; clearing site data or another device loses them.
Drop in a reference, calibrate the table to your own pencils, and print the map or the outlines.
Free · No sign-up · Runs in your browser