Cut Settings - Image Mode

This mode is only available for image shapes, and lets you choose options that control how LightBurn renders the image data on the laser.

The image above shows the settings available for images. Many of these will be familiar from Fill mode with the rest specific to image engraving. Note that on a CO2 laser it's likely that you will be running at a low power and/or very high speed, whereas a diode laser may be run at full power, depending on material.

These settings do not allow you to control things like image brightness or contrast. Instead those are set on a per-image basis and can be accessed via the Shape Properties panel.

To see a side-by-side comparison of the source and output image, while being able to change both the layer settings described in on this page and the image shape properties, checkout the Adjust Image tool.

Speed

See Speed Cut Settings Basics.

Min / Max Power

Max Power is the maximum laser power for pure black. Setting this to a lower value will decrease the power of the laser when engraving absolute black.

Min Power is only used when using the Grayscale image mode, and is the minimum power of the laser for pure white. Increasing this value beyond your lasers firing threshold will allow the laser to fire for absolute white.

Note: The min to max power scale will effect the entire range from absolute white to absolute black. If your image does not contain pixel values at these extremes the laser will never fire at exactly those min/max settings. So you may need to change this scale depending on the source image being used.

Bi-directional scanning

When enabled, the laser will engrave in a side-to-side sweeping motion, engraving in one direction and again for the return direction. When disabled, the laser will engrave traveling one way, then return to the start of the next line, not engraving the return pass.

Negative Image

This will invert your image during engraving. Light becomes dark, dark becomes light. This is useful for engraving slate or glass, where burned areas become lighter.

Overscanning

When enabled, adds extra moves to the beginning and end of each line to give the laser time to speed up before firing, and slow down afterward. If your machine has low acceleration or you see darker burns at the sides of your fills, you may need to increase the amount of overscanning. If you do not see this setting, your machine is likely a DSP controller and handles this automatically in hardware.

Line Interval

Controls the spacing between scanned rows, and indirectly controls 'DPI'.

DPI (Dots Per Inch)

Controls the pixel density of the output - this is simply another way of representing line interval that is more intuitive for some. DPI (dots per inch) is just 25.4 / interval.

Scan Angle

Normally 0, meaning the laser will scan back and forth horizontally across the image, progressing from the bottom of the image to the top. If you set this to 180, the laser will scan the image from top to bottom. Setting this to 90 will scan the laser vertically over the image, progressing from left to right.

NOTE: If you have a DSP controller, we do not advise using angles that aren't a multiple of 90 degrees. Horizontal and Vertical scanning is supported natively by the hardware, and it will automatically handle over-scanning beyond the sides of the image to get the head to full speed before engraving starts. Scanning at non-90 degree angles is "emulated" using normal cutting moves. It works, but it's mostly useful as a style option, and not recommended for general use.

Z Offset

If Z moves are enabled, this setting controls how much to raise or lower the Z axis when executing this fill. Lifting the laser a few mm, for example, can make the beam wider, allowing the use of larger interval values, which can make filling a large area faster.

Fill Grouping

These options control which images are filled at the same time on the laser. If you run your laser fast, OR your laser accelerates slowly, it is often most efficient to scan things all at once, so the laser spends most of its time moving at the speed you've chosen, and less time changing direction. If you are engraving slowly, or your laser accelerates fast, or the design contains a lot of blank space, it can be more efficient to fill clusters of close shapes, or just fill the shapes one by one. If you aren't sure, try different options and use the preview to estimate the time.

• Fill all shapes at once: The default, this setting means that everything on this layer will be filled at the same time, sweeping back and forth across the whole job. If you are running the laser fast (300 mm/sec or more) this is usually the most efficient option, with some exceptions.
• Fill groups together: This setting will fill all shapes in a group at the same time.
• Fill shapes individually: This setting fills all shapes one by one.

Cells per inch

Number of Halftone shading dots to compute per inch. Only enabled when the Halftone Image Mode is selected.

Halftone angle

Angle of the Halftone shading patern. Only enabled when the Halftone Image Mode is selected.

Number of Passes

How many times to repeat the entire engraving process.

Ramp Length

Length to ramp in and out of the sides of engraved features. Typically used for rubber stamps.

Pass-Through

This prevents the image from being resampled internally at all and disables the normal image modes described below. Line interval / DPI will be directly tied to the size of the image. This is best used for images that have been pre-processed for laser engraving outside of LightBurn.

Image Mode

The Image Mode setting is arguably the most important setting of them all for images. It will define what your resulting engrave will look like and there are many modes to choose from. Below you can see a description of all these modes, with an example of how that mode changes the look of thise original image.

Threshold

A simple on / off switch if the image is dark / bright at a given location. This should only be used for images that are two-color black/white to begin with, like an image you dithered outside of LightBurn. Don't use this mode for grayscale or color images.

Ordered

Also called ordered dithering, this is a step above threshold for grayscale images, and uses densely packed on/off dots to approximate shading, using an ordered/regular grid pattern. This is ok for general use, but works best for images with large areas of solid fill, where diffusion dithering can cause unwanted artifacts (see below).

Atkinson

A good "in between" mode for solid color or smooth shaded images. It resembles Jarvis but preserves detail better, though very light or dark areas may be blown out.

Dither

Also called error diffusion dithering, this is the best choice for smoothly shaded images, like photos. This also approximates shading with simple dots, but does so without evident patterning, and tends to produce more subtle shading.

Stucki

High quality dithering. Slightly faster than Jarvis and a good choice for smooth shaded or photo images.

Jarvis

High quality dithering. Usually the best choice for smooth shaded or photo images.

Newsprint

Emulates newspaper halftone. It has good shading, but is visibly patterned. Good for higher DPI settings, or Smoothieware controllers.

Halftone

Good quality shading for high DPI images. It is similar to newsprint but can have variable cell size and pattern angle.

Sketch

Useful for line drawings or handwriting as it tries to detect hard edges.

Grayscale

With a CO2 laser, this can achieve variable depth (3D engraving), not shading. Images typically need to be specifically created for this use. With a diode laser this can provide great shading but is harder to get right than plain dithering.

Note: when previewing a Grayscale engraving, be sure to check Shade according to power otherwise you will see a completely black preview since, unlike other modes, Grayscale scans every portion of the image, just at varying levels of laser power.