PHOTO PREPARATION GUIDE · RASTERGO
Preparing a photo for slate engraving
Updated October 2026 · Free browser tool · photos stay on your device
Slate usually shows a lighter mark against a darker surface, so the photo needs stronger local contrast and an inversion check before you commit. Prepare the image at the final physical size, compare it against the original, and run a small test piece first.
Why slate behaves differently
Slate is dark, mineral and uneven. The laser does not remove dye the way it does on paper; it changes the surface so the mark appears lighter than the surrounding stone. That means mid-tones are where most detail is lost, and a photo that looks fine on screen can flatten out completely.
Prepare the file
- Set the physical size first: width and height in millimetres, then the DPI your laser software expects.
- Crop so the subject fills the frame. On slate, small faces lose detail fast.
- Raise local contrast and check the shadow side. Slate hides dark detail more than bright detail.
- Compare the original and the processed image side by side before exporting.
The inversion question
Whether you need to invert depends on your input image and how your laser software interprets tonal values. Rather than assuming one switch is always right, export one normal and one inverted version and compare them on a test piece. The digital slate preview in RasterGo is a simulation of the material appearance, not a photographed engraving.
Before you run the job
- Run a small test tile with the same settings, not a corner of the real gift.
- Confirm the exported file opens at the physical size you set.
- Clean and dry the surface; dust and finger marks change how the mark reads.
RasterGo prepares image files in your browser. Material previews are labelled digital simulations, not photographs of engraved pieces, and no power, speed or physical result is promised.