Images

A picture, such as a logo, a scanned sketch or lettering, can be traced into shapes and then V-carved. Chipload turns it black and white, traces the edges between black and white, and puts the outlines on a layer of their own.

A picture of strokes, such as handwriting, a signature or line art, can instead be traced into the strokes’ centre lines and cut with a follow path.

Black is what gets carved: for a V-carve, black is the inside of the shapes. A light logo on a dark background needs invert.

PNG, JPEG and BMP pictures work, up to 20 MB and 20 megapixels. The picture is stored in the project, so its settings can be changed later.

Size and place

A new picture comes in half the stock’s width, with its lower-left corner at X0 Y0. Click it in the Browser (it is selected right after importing) for its properties:

• Position: the lower-left corner of its box, mm;
• Rotation: degrees counter-clockwise, any angle, about its centre, with ⟲ 90 and ⟳ 90. The picture is traced as it is and its shapes are then turned, so the trace doesn’t change; on the canvas the picture is drawn turned too;
• Width in mm; its height follows from the picture. Chipload doesn’t use the picture’s DPI, which is often missing or wrong.

On the canvas: with the picture selected, its box shows handles (in top view):

• the square in the middle moves it;
• the square beyond its right side turns it about its centre, in steps of 15°;
• a corner square makes it larger or smaller, keeping its proportions; the opposite corner stays where it is. Its width is rounded to 0.1 mm.

The box follows the cursor while you drag, and the picture is traced again when you let go, as one undo step. Hold Alt for no steps (any angle, any size) and no snapping.

On the command line, give --width, --at (the picture’s corner before it is turned) and --rotate.

Black and white

The traced shapes

• Smooth edges: the edge is traced where the blurred grey crosses the threshold, between pixel centres, so there are no pixel steps.
• Always valid: the outlines are always closed and never cross. A white part inside a black one is a hole, as in a pocket.
• Picture border: black that reaches the picture’s edge is closed along it, with a note: usually a background that wants invert.
• Too many shapes: a picture that traces into more than 5000 shapes (a photo, noise) is refused. Blur it more, raise the smallest piece or change the threshold.
• Arcs: with arcs on, the edges are fitted with arcs as well as lines, still within the smoothing: a traced logo becomes a few dozen pieces instead of hundreds of short lines. A profile, pocket or follow path of them is then cut with G2/G3 arcs: a smaller program, and smoother motion, since a controller slows down at every short line. A V-carve gains little: its moves are lines anyway. An outline whose arcs would come too near another one is kept as lines, and the report says so.
• Not editable: the shapes can’t be edited in Chipload.

Changing a setting traces the picture again and replaces its shapes, which get new ids. So an operation selects the image as a whole ("select": {"image": 1}), never its shapes one by one: Chipload refuses an operation that selects traced shapes by id.

The drawing’s placement moves only the DXF’s shapes, never a traced picture; a picture has its own X, Y and width.

Centre lines

With Trace: centre lines, each black stroke becomes a path along its middle: open, or closed for a ring like an O. A follow path cuts each stroke in one pass at the depth you choose, as wide as the bit, whatever the pen did. Select the image and Follow (ribbon, OPERATION).

• Junctions: where strokes meet (a T, a Y), their paths end at the same point.
• Ends: a path stops half a stroke’s width short of a round stroke end, at the middle of its curve, so a bit as wide as the stroke reaches the end. Small side branches from a rough edge or a square corner are tidied away.
• Stroke width: the report gives the strokes’ width (“Strokes 2.9 to 3.2 mm wide”), to pick a bit by.
• Dots (the point of an i, a full stop) are too small for a centre line. They are left out and counted in the report.
• For strokes only: a filled area’s centre line is a branching skeleton. That is correct, but rarely what you want; a wide range in the stroke widths shows it.
• Closed lines are outlines too: an outline drawn by hand and scanned traces as one closed centre line, and a profile or pocket can cut round it like any outline. The report says how many lines are closed.
• Open lines only for a follow path: a profile, pocket or V-carve of a picture whose centre lines are all open is refused, with a hint to use a follow path or trace the image as outlines. With both kinds, the open lines are skipped, with a note.

In the app

File > Import image… picks a picture and opens its window. A project is made first if none is open. Without a file dialog (see Install), File > Import image from path… takes the picture’s path instead.

• Left: the picture as black and white, updated as you change the settings: the dark parts are what is traced. With centre lines, the lines are drawn over it in orange. Scroll over it to zoom in at the pointer, up to 32 times, drag to move about, and double-click to see all of it again.
• Right: the conversion settings, and what was traced (with the threshold auto picked). The size, place and layer are not here: they are the picture’s properties.
• Import: puts the shapes into the project and selects the image, so V-carve carves them (or, for centre lines, Follow cuts them). It is one undo step.

Afterwards:

• Move or resize it: click it in the Browser and change its position, rotation, width or layer in Properties.
• Trace it differently: double-click it, or right-click it > Trace settings…: the same window opens (its button says Apply).
• Remove it: right-click > Remove removes the picture and its shapes.
• See it: Images on the canvas’s navigation bar (or View > Show images) shows the pictures faintly on the stock top, over the simulated stock and under the drawing, in top view and 3D, for comparing the traced shapes, and the cut, with the picture.
• Leaving shapes out: with the picture selected, Ctrl+click a shape to leave it out of the operation (What an operation selects).
• Operations: clicking traced shapes on the canvas and adding an operation selects the whole image, not the shapes.

On the command line

chipload image add part.chipload logo.png --width 120 --at 10,10 --threshold auto
chipload image add part.chipload signature.png --width 80 --trace centre-line
chipload image set part.chipload 1 --threshold 140 --blur 2 --invert true --arcs false
chipload image set part.chipload 1 --rotate 30         # turned 30° about its centre
chipload place part.chipload --image 1 --at 10,10      # as for a DXF: --at, --rotate, --width
chipload image list part.chipload
chipload image preview part.chipload 1 -o bw.png
chipload image remove part.chipload 1

• image add: the layer is the file’s name unless --layer says otherwise. It reports how many shapes were traced, the threshold, the specks dropped, and whether black touches the border; for centre lines also the stroke widths and the dots left out.
• image preview: writes the black-and-white picture exactly as it is traced.
• chipload set: also reaches the settings (drawing.images.0.threshold=140). The image is then traced again, as with image set, also for --set on a single run.

In the file

drawing.images in the project file: id, file, sha256, data (the picture, base64), layer, x, y, width, threshold (a number or "auto"), invert, blur, min_area, smoothing, trace ("outline" or "centre_line"), arcs. The traced shapes are path shapes with "image": id. Images in projects from Chipload 0.15 open as outlines without arcs, exactly as they were traced.