Different results when generating image two different ways

I imported 2d barcodes from courier tickets two different ways:

  1. A PDF printout of the courier ticket was imported. It automatically identified the QR code as an image. That is the darker code in the attached file.
  2. A PNG printout of the courier ticket was imported. The image was converted to path using the attached settings. I then converted the barcode to bitmap (right click-convert to bitmap), using “Fill” with about 800dpi.

The results - 1 engraves faster (doesn’t decelerate/accelerate between dots; only at the edges). It is also slightly darker in the centre and obviously at the edges. It is also more sharply defined at the edges of the dots.

In both cases, 50mm/sec @45% power, on the same corrugated brown cardboard. I checked each object properties - they are the same.

I’m just curious why this might be, and if there is a way to get the same results as 1 using correct settings with method 2 above?

Neje 2 Master 20W 170x170 (150x150), Firmware V7
Lightburn 0.9.19

2d barcode differences.lbrn (94.7 KB)

You wrote, “The image was converted to path”, then you converted it back to an image - That’s a little but like taking a CD, recording it to a cassette tape, then burning that back onto a CD.

Image tracing is not a perfect process, and will introduce artifacts, so you’re better off just leaving it as an image and burning it using ‘Threshold’ mode.

You should also enable “Overscanning” in the image or fill settings, as that will make the laser overshoot the sides a little after turning off the beam, and will prevent the darker burn on the edges.

Hi Oz. Thanks for the explanations. I had figured as much regarding the edges of the double converted image. However it was surprising to me that the centres of the features were lighter. I would have thought that they would be about the same darkness with the same size & burn settings. Will try other ways.

Thanks for the overscanning tip, will try it out.

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