How to Use LightBurn Pass-Through With a Dithered Image

What Pass-Through is for

LightBurn's Pass-Through option is designed for images that have already been processed for engraving. Instead of resampling the source and applying one of LightBurn's image modes, it uses the prepared pixel pattern as-is.

This is the correct boundary when EngravePrep or another editor has already produced the final one-bit dither. The exported dots are artwork, not an intermediate grayscale photo.

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Finish these decisions before import

Crop, tone, polarity, dither, physical dimensions, and intended DPI should be settled before the handoff. The pixel grid must match the final job rather than an arbitrary large export.

For example, a 4 inch image prepared at 254 DPI should be 1,016 pixels wide. If the destination changes that relationship, each prepared pixel no longer maps cleanly to the intended scan spacing.

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A careful Pass-Through workflow

Interface labels can move between LightBurn versions, so use the current Image Mode documentation for your installed version. The underlying checks remain stable.

1. Import the PNGBring in the full-resolution, externally dithered file rather than a screenshot or shared preview copy.
2. Set the physical sizeConfirm width and height match the values used during preparation. Keep aspect ratio locked.
3. Open image settingsSelect the image layer and enable Pass-Through for the prepared bitmap.
4. Confirm polarityApply negative engraving only when the material response requires it, and apply it only once.
5. Set machine valuesUse a tested speed, power, focus, and interval for the laser and material.
6. Preview closelyVerify that the expected dot field remains and that the job dimensions are correct.

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When not to use Pass-Through

Do not use it for an ordinary color or grayscale photo that still needs LightBurn to create the engraving pattern. In that case, choose the appropriate Image Mode and use LightBurn's Adjust Image workflow.

Do not use it as a shortcut around resolution planning. Pass-Through preserves the supplied bitmap, including mistakes. If the file was prepared at the wrong dimensions, has gray pixels, or contains a damaged dither, return to the source and export it again.

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Pass-Through, Threshold, and photo dithers solve different jobs

Pass-Through is a preservation mode. It assumes the imported pixel grid is already the finished output. Threshold is a conversion mode: it decides whether each incoming value falls on the black or white side of a cutoff. Jarvis, Stucki, Dither, and Ordered are tone-simulation modes that create new mark patterns from a grayscale or color source.

A strictly binary file may look similar under Threshold in a simple preview, but that does not make the workflows interchangeable. Pass-Through states the intent clearly and ties the scan spacing to the prepared image. It also makes troubleshooting easier because there should be no second tonal decision between the exported pixel and the machine job.

If you want to use LightBurn's brightness, contrast, gamma, or dither controls, import the original continuous-tone image and let LightBurn own that preparation stage. If EngravePrep owns those decisions, import the final one-bit PNG and let LightBurn own placement, machine settings, preview, and execution. Choose one editor to own the dot pattern.

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Common handoff failures

A solid or nearly solid preview can be a zoom problem, a polarity problem, or a sign that the image is being processed differently than expected. Zoom into the preview until individual scan behavior becomes visible and compare it with the exported bitmap.

Unexpected softness or a new pattern usually points to resizing, interpolation, or a second dither. Incorrect physical size often comes from resolution metadata being interpreted differently. Confirm actual pixels, intended DPI, and displayed dimensions together.

• Do not use a messaging-app thumbnail in place of the exported PNG.
• Do not resize a finished one-bit dither for a different product size.
• Do not enable both an external dither and a destination dither.
• Do not assume preview inversion changes the engraving signal.

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Pass-Through does not choose machine settings

Preserving pixels does not determine safe or effective speed, power, interval, focus, airflow, or material handling. Those remain part of the machine process and must be tested for the laser and blank.

The cleanest troubleshooting approach is to keep the prepared bitmap fixed while calibrating the physical process. Once the machine can reproduce the strip predictably, compare image variants without moving the machine variables at the same time.

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