LightBurn Tutorial 08 – Basics: Image Trace

The Lightburn Software Series

The Lightburn Software is probably the best generic laser cutting software available (I use it for almost all of my laser work). This series has tutorials, hints and tips as well as the occasional speed comparisons between it and RDWorks. In this LightBurn Tutorial session, we learn how to use Image Trace.

My thanks to the team at Lightburn for allowing me to embed their videos.

Contents

How to use the Image Trace tool in LightBurn.

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LightBurn Tutorial Image Trace
LightBurn Tutorial Image Trace

Transcript for LightBurn Tutorial Basics – Image Trace

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0:00image trace in light burn is one of the

0:02more useful tools that we have available

0:03it’s also very easy to use compared to

0:06what you may be used to in other

0:08software so in this video we’ll cover

0:10the basics and then we’ll show you how

0:12to use the more advanced options so what

0:14is image trace image tracing is

0:17essentially converting pixels into

0:20vector shapes

0:21if you’ve ever zoomed in on an image

0:24like a JPEG or a PNG file you’ll see

0:26that an image is just a grid of shaded

0:30squares these are called pixels and each

0:33one of them will have a brightness value

0:35or a color assigned to it there are no

0:38shapes exactly it’s just a regular grid

0:41of dots with shading this is great and

0:44for example this image the laser would

0:46have no trouble engraving scanning back

0:48and forth and turning on and off as it

0:50encounters dark areas but the problem

0:53arises when you want to cut something

0:54like this out there is no path for the

0:57laser to follow to tell it to cut the

1:00outline of this for example so image

1:02trace allows you to recover shapes and

1:05vectors from an image like this to

1:08access the image trace feature in light

1:09burn select the image and either go to

1:12tools trace image use the hotkey alt T

1:16for trace or you can select the image

1:19right click and go to trace image in the

1:21pop-up menu and you’ll be presented with

1:24light burns image trace dialog in this

1:27window here you’ll see purple outlines

1:30showing me the vectors that light burn

1:32has found in this image and often this

1:36is all you’ll need to do bring up the

1:39image trace check it to make sure that

1:41the result is what you want click OK and

1:44you’re essentially done this image now

1:47has a vector outline dropped right on

1:50top of it in the same place light burn

1:52will do that for you and you can see

1:54here I’m only seeing the wire outline of

1:57this image but if I switch light burn to

Transcript for LightBurn Tutorial Basics – Image Trace (Cont…)

2:01showing me the filled rendering you can

2:04see that they match nearly exactly and

2:07if i zoom in I’m no longer seeing those

2:10jagged pixel outlines I’m seeing nice

2:12smooth

2:13Irv’s here on this shape on the left and

2:16that is because this shape is now made

2:19of curves and lines instead of

2:21individual dots as a grid and so this

2:25can be engraved the same way that you

2:26would an image but it can also be cut I

2:29can recover these vector lines if I

2:32switch back to my standard wireframe

2:35view I could ungroup this take this line

2:39and set it to cut for example so that I

2:42could cut this out I could offset it I

2:44can do other operations that I couldn’t

2:45do on the original image that’s the

2:49basic operation of light burns image

2:52trace feature I’m just going to remove

2:54this one and go back to this show you a

2:59few more advanced options so first of

3:02all when you are looking at the image

3:04here sometimes it can be difficult if

3:06the image is busy to see the lines that

3:10the software has created for you if you

3:12click the fade image button down here at

3:15the bottom it dims the image so that you

3:18can more easily see the vector shapes

3:20this is a great way for you to spot

3:23check things make sure that everything

3:24looks right there’s also show nodes or

3:28show points so you can see the

3:31individual nodes or vertexes that the

3:34software is adding to your shape you can

3:37also see whether things are curved or

3:39not so for example here at this tight

3:42corner you can see that the software is

3:44making a curve there if the software

3:48creates shapes that are too sharp or too

3:51smooth you can adjust the smoothness

3:53value here pixels don’t have curvature

3:57exactly so the software is trying to

3:59figure out the best possible shape that

Transcript for LightBurn Tutorial Basics – Image Trace (Cont…)

4:03fits your image intuitively I guess and

4:07it’s there’s not always a perfect answer

4:09so here for example it’s chosen to make

4:11a sharp corner that looks correct here

4:14it’s chosen to make a round shape that’s

4:16probably correct sharp corner here sharp

4:19corner here and so on but there may come

4:21places where the decisions aren’t quite

4:24so clear

4:25and so you can choose to increase or

4:29decrease the smoothness value here which

4:32adjusts where and how those decisions

4:35are made so for example this corner

4:37right now is smooth if I lower my

4:41smoothness number enough it becomes a

4:43corner and so you can tune this value to

4:46match the image and that’s useful

4:48sometimes if you’re trying to capture

4:50small texts or things like that that

4:52have sharp corners where there’s not a

4:54lot of detail and the software’s having

4:55a hard time making the right the right

4:57call there’s also a value here called

5:00optimize this controls how many nodes

5:03get added to the vectors that it creates

5:06and so if you set this down to zero you

5:10can see that it’s created quite a few

5:12points around this shape here for

5:14example if I increase the optimization

5:18value you’ll see that more and more of

5:22those nodes get discarded and sometimes

5:26it may affect the quality of the fit so

5:30for example at an optimization of zero

5:32this is the best possible outcome that

5:35the software is able to come up with as

5:37I increase the optimization number it

5:41discards more and more points but you’ll

5:43notice that in some places it doesn’t

5:45quite fit as well as it did before so

5:47here for example it’s starting to slip

5:49off of the shape a little bit as you

5:52lower this number

5:53it’ll probably increase or get better

5:55and see there you can see now it’s a

5:57better fit so play with this in most

Transcript for LightBurn Tutorial Basics – Image Trace (Cont…)

6:00cases the default value of 0.2 is a good

6:03balance between the quality of the fit

6:06and the number of points in the output

6:08and so you probably don’t need to change

6:10it much but it’s good to know that it’s

6:12there there are other options as well in

6:18most cases you’ll go trace image the

6:22spot check it hit OK drag the original

6:25out of the way and or delete it if all

6:28you want is the vector traced result so

6:31there’s a helper that will make that

6:34just a little faster if I go to trace

6:36and I say delete the image after trace

6:39when I hit okay light burn has removed

6:42the bitmap for me and now I’m just left

6:44with the trace so it’s a simple thing

6:46but it saves you a step there are a

6:51couple of options in the trace feature

6:53that are a little more advanced and

6:55we’ll show what those are and how they

6:57work so the first one is threshold

7:00threshold controls which portions of the

7:03image are things that you want traced

7:05and which portions will be discarded

7:07this is not something that you would

7:09likely trace this is just a gradient but

7:12it’s an excellent demonstrator for the

7:14threshold and cutoff values right now by

7:18default light burn is set to a threshold

7:20of 128 that’s half of the possible 255

7:24shades and brightness so it’s going to

7:26capture everything from pure black up to

7:30128 brightness and anything from 128 up

7:34to 255 brightness is discarded as I

7:38slide the threshold downward I’m now

7:42narrowing which brightness values light

7:45burn is catching or tracing so now it’s

7:47only going to trace around the darkest

7:49blacks for example as I increase this

7:52it’s going to trace more and more into

7:54the gray areas and potentially all the

7:57way up to white so if you have an image

Transcript for LightBurn Tutorial Basics – Image Trace (Cont…)

8:00that has shading or shaded edges like

8:04this one if i zoom in you can see that

8:06there is gray here in these edgings

8:09anti-aliasing or shading was applied to

8:11this image to make it smoother and

8:13adjusting the threshold will let you

8:15catch more or less of that detail

8:19similarly there is a cutoff value and

8:21the cutoff chooses where the brightness

8:24starts so it’s effectively the opposite

8:27of the threshold or the bottom end so

8:30with these two controls I can slide

8:33threshold all the way up to pure white

8:35and bring the cutoff value up to the

8:37middle and then I’m only tracing now

8:39from mid gray to the brighter white this

8:43allows you to narrow in on specific

8:45shading regions within your image so

8:47going back to our cartoonish Rhino here

8:50if I open the trace if I was to want to

8:55trace this gray section in this

8:58independently of the rest of the image

9:00let’s say that I wanted to take this

9:02image and do a couple of passes over it

9:04and engrave this gray with a different

9:07pattern than the rest of it I can

9:09capture that by playing with my

9:12threshold slider until I’m catching one

9:16part of it so now I’m gonna turn the the

9:18fade on so I can see what’s being caught

9:21right now so I’m grabbing from purest

9:23black up to some level of gray here as I

9:28pull this down you can see this line

9:31pops from here to here so I’m crossing

9:34the threshold here where it captures

9:37from this dark black in the original

9:39image to this darker gray and so that’s

9:43that’s a good spot there for my

9:45threshold and now if I bring the cutoff

9:48up I’m going to skip over these black

9:52areas and just capture these Gray’s

9:54which is actually what I want now you’ll

9:57also notice that because this image has

Transcript for LightBurn Tutorial Basics – Image Trace (Cont…)

10:00shading there are spots here that fall

10:03into that same band of gray that are

10:07being caught as well and I don’t want

10:09these now I could manually edit the

10:12resulting image after I’m finished but

10:15there’s an easier way light burn has

10:17this ignore less than value here this

10:21basically says that any isolated region

10:25that is smaller than this number of

10:27pixels gets discarded so right now it

10:29says anything smaller than two gets

10:31thrown away so anything that’s a single

10:33pixel in size will get discarded that’s

10:35obviously not large enough for these so

10:38if you increase this say make it 20 now

10:42you’ll notice that all of those little

10:44strays here are gone if I bring it back

10:46to two you can see there’s a bunch of

10:48them here set it back up to 20 and those

10:51are gone there’s still one here so 20 is

10:54not quite enough

10:55so let’s bump that up again say 40 I’m

11:00gonna fade this again so that I can see

11:02a little easier where

11:04my results are I don’t know there’s one

11:07all right so let’s just go all the way

11:09up to a hundred that looks good

11:13I’ve got only the regions that I’m

11:15interested in capturing turn off the

11:18delete image after trace because I want

11:20to do another pass over this hit okay

11:23and my first result is now captured now

11:28I can select the image and go to trace

11:31again and this time I’m only interested

11:34in just the black outlines so I’m going

11:37to pull my threshold down until I’m

11:40capturing all the black hit okay and now

11:43I have the dark shading and the black

11:47outlines as two separate pieces and if I

11:50grab this one and pull it away you can

11:52see that that other section is still

11:53there I can make this a different layer

11:57for example change the fill setting

Transcript for LightBurn Tutorial Basics – Image Trace (Cont…)

12:00change the power that’s being used and

12:02so on and so I could engrave this image

12:05as a two-tone with multiple passes and

12:09get the shading effects that I want so

12:12I’m undoing a bunch of things here now

12:14so I can show you a few other options

12:16trace image also allows you to define a

12:20boundary so if I was only interested in

12:23capturing say the face of this and not

12:27the rest if I click and drag out a

12:30rectangle the trace feature will only

12:33capture what’s in that rectangle and

12:35ignore everything else and so that can

12:36make editing your result or capturing

12:39only the things you’re interested in

12:40much simpler it won’t be perfect you’ll

12:43see I’m catching a spot down here and a

12:46little bit up here that I don’t want if

12:48I’m just trying to catch the face but it

12:50means a lot less editing of the end

12:52result if you are capturing from the

12:54camera for example and the resulting

12:57image has a lot of noise or a lot of

12:59visible bed area things like that

13:01so dragging a rectangle out allows you

13:05to narrow in what you are capturing and

13:09makes the editing process simpler after

13:12you’re done if you accidently drag the

13:15rectangle you can single click anywhere

13:17or double

13:18click to clear it you can also edit the

13:21rectangle after it’s been dropped by

13:23just clicking and dragging on any of

13:24these points and you’ll see that it

13:27makes a makes a much tighter fit so I

13:31can grab just the nostrils for example

13:33just the eyeballs and so on

13:39and there’s what we’re left with and so

13:42this would be much faster to edit out

13:44than trying to edit everything as a

13:48result of that trace if I didn’t want

13:49the whole thing now there’s one more

13:53feature of the trace in light burn

13:55that’s worth mentioning if you do a lot

13:59of work with handwriting for example old

Transcript for LightBurn Tutorial Basics – Image Trace (Cont…)

14:02recipes things like that engraved onto

14:05cutting boards there’s a feature in the

14:07trace that can help you so looking at

14:10this you’ll notice that the lighting

14:13across this photo of a handwritten

14:16recipe is not uniform it’s not

14:19consistent and so it gets its light up

14:21here and it gets darker down in the

14:22corner and a traditional trace is going

14:25to have a hard time catching just to the

14:27writing so as I move the threshold value

14:30around you’ll see that it’s catching all

14:32of this dark area here because it’s dark

14:35if I pull the threshold down enough now

14:38I start losing the lighter bits of the

14:41text and that’s a problem and it’s a

14:44problem in most software however light

14:46burn has a feature called sketch trace

14:48which looks for sharp edges and

14:50transitions in lighting and ignores the

14:53overall lighting and it’s actually

14:55designed for recipes and handwriting so

14:59now this threshold value becomes sort of

15:03a detail size or how much difference

15:07there is between the dots for it to be

15:10considered an edge so if I scroll this

15:12up you’ll see that it’s starting to skip

15:15smoother areas of the image here but

15:17it’s still catching most of the

15:18handwriting if I scroll it down far

15:20enough it’ll actually start capturing

15:23the noise as well as the handwriting

15:26that I’m interested in and so through a

15:29combination of adjusting the threshold

15:31value here

15:32and tweaking this ignore less than

15:34number you can do a lot of handwriting

15:41recipes

15:42fairly easily so this one I’m still

15:46catching a fair amount of the detail

15:47over here I’ve got almost all of that

15:50handwriting well captured and recognized

15:53hit okay and drag this away if I preview

15:58the result here oops so this actually

Transcript for LightBurn Tutorial Basics – Image Trace (Cont…)

16:03has captured the outline which is going

16:07to require some editing or a little bit

16:12easier I can just put a box around the

16:13whole thing and now if I preview turn

16:19off the show traversal moves you can see

16:21that the end result is actually quite

16:22legible readable and you know with a

16:25little bit of editing would be pretty

16:26clean especially given the quality of

16:28the original image so none of the

16:30strange shading is in here and with a

16:32little cleanup this would be quite

16:34appropriate for an engraving that pretty

16:37much covers it so thanks for watching

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