I maintain this tool.
I maintain RasterGo, a free browser tool for preparing photo PNGs for laser engraving. This guide covers image preparation, not a tested power/speed recipe or a guarantee of an engraving result.
Start with physical size
For a 100 mm square image at 300 DPI:
pixels = round(mm / 25.4 × DPI)
round(100 / 25.4 × 300) = 1181 pixels per side.
That specifies the digital image size. It does not prove that 300 DPI is best for every laser, material or focus setting. Upscaling also cannot restore detail missing from the original photo.
Crop and adjust before dithering
Use a crop that keeps the face and important details clear at the final size. Adjust tones while comparing the original and processed image. A busy background can obscure a subject after dithering. Avoid treating a dramatic preview as proof of a good physical result.
Decide which application handles the image
Dithering turns tones into a pattern of dots. If you export an already dithered image, check the image mode when importing it into your laser software; applying another tonal conversion can change the pattern. LightBurn documents its image modes here: https://docs.lightburnsoftware.com/latest/Reference/CutSettingsEditor/ImageMode/ . Follow the mode appropriate for your own workflow and test it.
Slate needs a material test
Slate usually reveals a lighter mark against a darker surface. Whether your pipeline needs inversion depends on the input and software settings. Check the preview and a small test piece rather than assuming that one invert switch works universally. Digital material simulations on RasterGo are labeled; they are not photographed customer engravings.
Export, import and confirm
In RasterGo, choose the image, set size and DPI, compare the crop and tone adjustments, then export the PNG. The image processing stays in your browser. On import, confirm the physical width/height and inspect the result before running the machine. The tool also supports a small batch ZIP workflow.
I am looking for practical feedback from makers: did the exported file keep the intended size, and which preparation step still required manual work? Free beta; no calibrated machine settings or physical engraving result are being claimed.
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