Image Mode
Image Mode is a special engraving mode for images, which works similarly to Fill Mode, but allows you to select an additional image processing mode that affects the appearance of the engraving.
Speed, Power, and Line Interval are all crucial settings for achieving great image engravings, but the appropriate settings are heavily dependent on your laser and material.
Several additional settings that affect the quality of the engraving are applied on a per-image basis, using the Adjust Image tool or Shape Properties Window.
Image Mode Settings¶
There are several specialized options available in the Cut Settings Editor for layers set to Image Mode. All settings are located in a single Image Settings tab.
Note
See Main / Shared Settings for information on applying essential settings like Speed and Power.
See Additional Options for information on specialized settings not covered on this page.
Click any option in the image below to jump directly to the relevant section for that option, or scroll down for a list of options and descriptions.
Some of the settings presented in the images below are available for users with specific kinds of lasers, but most are shared between all types of lasers.
Bi-directional Scanning¶
When enabled, the laser will engrave in a side-to-side sweeping motion with the laser on and engraving in both directions.
When disabled, the laser will engrave while traveling in one direction, then return to the start of the next line without engraving the return pass. Depending on the type of laser, enabling this can save significant time on long engraving jobs.
Bi-directional vs. Uni-directional Scanning Comparison
Negative Image¶
This will invert your image during engraving. Light becomes dark, and dark becomes light. This is useful for engraving slate or glass, where burned areas become lighter.
Tip
Use this in conjunction with the Invert switch in the Preview window to see how your engraving will look on dark surfaces.
Overscanning¶
Note
This switch is not available for DSP controllers or Galvo lasers. DSP controllers handle Overscanning automatically, while Galvo lasers compensate for extra burning at edges with Delay settings.
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. Overscanning distance is calculated as a percentage of Speed.
When Overscanning is not used or not set correctly, engraved jobs appear more burned at the edges and lighter in the middle, due to the laser slowing down to change scanning direction, while firing.
LightBurn can compensate for this by running the laser head outside the boundaries of the engraving, but with the laser off. This maintains an even speed on the engraving itself to provide a consistent engrave. You need a little more space on either side of the engraving to accommodate this Overscanning.
Excessive Overscanning: GCode
If Overscanning is enabled on a GCode laser and there isn't enough room at the edge of the job to accommodate the extra travel distance, you may see LightBurn's Cut May Be Out Of Bounds error, or your laser's controller may return an ALARM:2 error.
To correct the error, reduce Speed or Overscanning distance, or move your graphics in toward the center of your Workspace, if you are using Absolute Coordinates positioning. If you are using Current Position or User Origin to set a custom Origin, set it closer to the center of your laser's work area.
Excessive Overscanning: DSP
DSP controllers handle Overscanning in hardware, but the Speed value you enter affects the amount of distance required. If a job on a DSP laser requires Overscanning and there isn't enough room at the edge of the job to accommodate it, your DSP controller may return the Not Enough Extend Space error.
To correct the error, reduce Speed or move your graphics in toward the center of your Workspace, if you are using Absolute Coordinates positioning. If you are using Current Position or User Origin to set a custom Origin, set it closer to the center of your laser's work area.
Overscanning Demonstration
Line Interval¶
Controls the spacing between scanned rows, and indirectly controls DPI.
Optimizing Line Interval
Lower Line Interval values lead to a greater density of lines. The ideal Line Interval will produce lines that just touch, without overlapping.
Increasing Line Interval to the maximum amount that doesn't leave gaps between lines will lead to reduced runtimes for your projects, with no loss in quality, but you may also need to increase Power to achieve dark engravings.
Use the Interval Test or Material Test to find the optimal Line Interval for your laser and material.
DPI (Dots Per Inch)¶
Controls the pixel density of the output — this is another way of representing Line Interval. DPI is 25.4 / Line Interval.
Dot Width Correction¶
Dot Width Correction compensates for the thickness of the laser's beam by shortening the length of engraved scan lines. The ideal Dot Width Correction value is about half the total thickness of the laser's beam. Due to varying affects of power output on different materials, this ideal value can vary depending on the material you're working with.
The number should always be smaller than whatever you’re using as your interval setting. The valid range is from 0 to your Line Interval value.
Scan Angle¶
Scan Angle defaults to 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.
DSP Scan Angle Warning
If you have a DSP controller, we advise only using scan angles that are a multiple of 90 degrees. Horizontal and Vertical scanning is supported natively by the hardware, and it will automatically handle Overscanning 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 you have Z movement enabled, and your controller supports it, you can use the Z offset setting to move the laser head closer to the material (inward) or farther away from it (outward). Positive values move the Z Axis inward, and negative values move it outward.
Focusing deeper into the material can sometimes help to cut thicker material, and lifting the laser away from the material can produce a thicker line.
Warning for Z Moves
Z moves have the potential to physically damage your laser by crashing the head into the material.
If your system uses auto-focus, you may not be able to push the focus point lower, because most systems treat the auto-focus height as the lowest possible height (Z limit) to avoid crashing the laser head.
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 pattern. Only enabled when the Halftone Image Mode is selected.
Number of Passes¶
How many times the laser will repeat the shapes on this layer. Sometimes, when cutting thick material, trying to engrave very deep, or using a lower power laser, more than one pass may be necessary.
Ramp Length¶
Use this setting to slope the sides of an engraving by varying the laser power. The ramp length controls how far from the design the slope will extend.
This setting is useful if you create rubber stamps, particularly if the designs have thin regions that need extra support.
This setting is only available if you have Threshold Image Mode selected.
Note
On a DSP controller, the Ramp varies the laser power from Min Power to Max Power, so you must set these differently to get a ramped side. Typically, you should set Min Power to be just above the firing threshold of your laser.
Pass-Through¶
When working with images that have been pre-processed for laser engraving, enable this setting to engrave the image as-is, rather than resampling using the Image Modes described below. Line Interval/DPI will be directly tied to the size of the image.
Image Mode¶
The Image Mode setting controls how LightBurn processes your image. Below you can see a description of each Image Mode in LightBurn, along with an example of how that mode changes the look of the example image. Click on the image previews to see a larger version.
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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, such as an image you dithered outside of LightBurn. Don't use this mode for grayscale or color images.
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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).
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Atkinson¶
A good "in between" mode for solid color or smooth shaded images. It resembles Jarvis but preserves detail better, though struggles to show detail in very light and dark areas.
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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.
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Stucki¶
A good choice for smooth-shaded or photo images, with slightly faster processing than Jarvis. Stucki works somewhat similarly to Dither mode to produce smooth shading, and likewise struggles in midtones. -
Jarvis¶
Generally the best choice for smooth-shaded or photo images, with slightly slower but better processing than Stucki. Jarvis works somewhat similarly to Dither mode to produce smooth shading, and doesn't struggle with midtones. -
Newsprint¶
A decorative pattern that imitates newsprint halftoning by generating a grid of spots that are larger in darker areas. It has good tonal range, but is visibly patterned. Smoothest shading is achieved with 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.
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Sketch¶
Useful for line drawings or handwriting, as it tries to detect hard edges. Sketch engraves only at the areas where light and dark values meet at hard edges (highpass filtering).
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Grayscale¶
Varies power output as a percentage between Min and Max Power, using Min Power for the lightest shades and Max Power for the darkest. With a diode laser this can provide great shading but is harder to get right than plain dithering. With a CO2 laser, grayscale mode can achieve variable depth (3D) engraving rather than shading. Images typically need to be specifically created for this use.
Note
When Previewing a Grayscale engraving, be sure to enable 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.
Fill Grouping¶
These options control which shapes are engraved at the same time by 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, 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 to fill the shapes one by one.
Tip
If you aren't sure, try different options and use 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.
Override PWM Frequency¶
If you have an RF Excited tube, this setting allows you to control the PWM frequency of the pulses sent to the laser, and can change the edge finish on certain materials.
Note
This setting is only available for lasers with Ruida controllers.
U Offset¶
Enter a distance here to set a per-layer U Axis offset. To use this setting, your laser must support U Axis control, and you must enable the U Axis in Device Settings.
Note
This setting is only available for lasers with Ruida controllers.
Additional Options¶
The settings presented in the Cut Settings Editor depend on the selected Layer Mode and the type of laser you're working with. Select an option below to learn more about different groups of settings.
Note
Some options in the Cut Settings Editor are hidden if you have Beginner Mode enabled.
For more help using LightBurn, please visit our forum to talk with LightBurn staff and users, or email support.