How to Convert an Image to HPGL
Learn how to convert any PNG, JPG, or BMP image to HPGL PLT format for pen plotters, vinyl cutters, and CNC machines. This step-by-step guide covers the full workflow from raster image to plotter-ready file.
About How to convert image to HPGL
HPGL (Hewlett-Packard Graphics Language) is a 2D plotter command format. Plotters, vinyl cutters, and some CNC machines take HP-GL or PLT files as input. Raster images like PNG and JPG are not directly usable — they must be converted to vector paths first.
Full image to HPGL conversion workflow:
Step 1 — Vectorize the image Upload your PNG, JPG, or BMP to the vectorizer. Select the colour count that matches the image complexity. Download the SVG output — this contains all the vector paths the plotter will follow.
Step 2 — Clean up in Inkscape Open the SVG in Inkscape. Run Path > Simplify to reduce node count. Excess nodes cause slow, jerky plotter movement and may exceed plotter memory limits on older machines. For plotters running a single pen, merge all paths to a single colour layer.
Step 3 — Export to HPGL In Inkscape: Extensions > Export > HP-GL (if the extension is installed), or File > Save As > PLT. Set the resolution to match the plotter (most use 1016 or 3048 units per inch). Adjust page scaling to the physical output size.
In CorelDRAW: File > Export > PLT format. Configure pen assignments and scaling in the dialog.
Step 4 — Transfer and plot Copy the PLT file to the plotter via USB, serial, or network. Load the media and run the job.
Common HPGL units: one HP-GL unit = 0.025mm (40 units per mm = 1016 per inch).