Remove corners from photo

Wait… I think I got it. I rasterized it after masking and I think that’ll do it.

I guess now my question is, does rasterizing a rastor image alter it? I don’t see a difference on-screen, but maybe my old eyes just can’t see it.


Thanks. Yeah, I thought of that. But I couldn’t figure out a way in Photoshop to exactly select the center of the selection to the corner I was working with.

the photo starts as a raster, so unless you shrank or stretched the image, it should be similar to the original.

1 Like

Thanks for your advice!

1 Like

Rasterizing in Inkscape resamples the image at whatever dpi you choose. Illustrator may have a similar option.

Sailbyc has a point, but the export dpi matters as well.

If I import a source image that’s 1000px by 1000px and then resize it to be 5”x5” in my svg, the effective dpi is 200. If I export the clipped raster at any other dpi it will definitely be modifying the source.

Theory follows:
Personally I’d probably try to export at an even multiple of the source dpi (200, 400, 600, etc). It seems like this would be the least intrusive way to modify the source. However, if I can’t work out the effective dpi, I’d at least try to make it higher than my intended engrave LPI. Conventional wisdom says 1.5x lpi, but I’m not sure why people have suggested that.

1 Like

The Glowforge is essentially a printing press when doing a project using Convert to Dots; like a printing press in that “ink” or the burn, is either on or off, at whatever specified power level.

Here is a pretty good paper on printing resolutions:

There are a ton of factors in play, and it really depends on how anal you want to be throughout the whole process as far as resampling, scaling, etc.

I do have a post here somewhere that shows the output difference between different input resolutions (600 points, 300 ppi, etc. at whatever LPI). The test could definitely be taken further as I only printed at one LPI using a few different PPI source images.

(Found it: Preparing a Photo for Raster Engraving (NOT NECESSARY FOR GLOWFORGE)) I think I should have tested it using convert to dots. Maybe not. Too early to think much. Regardless, you can certainly see the difference in the output

Illustrator does have a nice feature that shows the resolution (PPI) of an image when you have it selected, and you can see how it changes resolution as you scale it up and down.

All those things aside, the easiest way to do this, in my eyes, is to, as you found out, just use a clipping mask and then rasterize the clipping mask.


Likewise I have a post about testing lpi limits in baltic birch; your results are inherently tied to your material.

Each material will have a maximum possible resolution that you can engrave beyond which higher resolution just won’t get any better result.

Also I can see how the dithering routine in dots would be highly affected by the source DPI. I almost always use vary power when engraving and so it’s probably not apples to apples… the exception being on tile. Dots gives me a better result there, YMMV.

1 Like

Your testing process needs work, like mine :slight_smile: but it gives a good enough idea of what’s going on.

But I’m usually not organized enough to test scientifically. I like to fly by the seat of my pants or something. I’m also generally not as worried about microscopic pixel analysis - because viewing distance is a big factor that is typically ignored. That said, I do pay attention to image resolution (though I’m not particularly anal about it has to be exactly this to that).

Something to be viewed at 6 inches has different requirements than something viewed at 6 feet, and so on.

Some of the things we don’t know are what the software does in the background in different situations. What happens when you Add an image via artwork and scale it down? Is it just treating it as browser resolution, or maintaining the full resolution and resampling? Embedded into PDF or SVG, I’m pretty positive it respects the actual resolution. Conversely, what happens when you scale it up in the UI? We don’t know for sure the scaling methodology used, and the success of upsampling can vary widely between programs.

1 Like

Hi Tom
Clipping masks have been a pain for me, too. You can dismiss that warning, then ignore the pane on the left hand column in the GUI where that mask shows up. It will process your print that way. I’ve been doing things that way for quite some time. It used to be that you couldn’t even use an option like that, but somewhere along the way, that changed.


True. But if we do empirical testing we don’t really need to know. The tricky part is that GF can change their algorithms at any time (and did once before, ages ago) and invalidate any of our fumbling research.

And I totally agree with you about viewing distance. Generally I just export at 300dpi and am done with it. I get good results in almost all cases.

My source was 300 DPI and, yeah, I just selected 300 when I rasterized. I did see some sort of… shifting… can’t really describe what I saw. Al I can say is I saw a change, but I didn’t see quality degrade from what I could see. And then I figured “It’s wood. I’m only going to get so much “resolution” out of wood.”

I would have done that, except the two objects it showed me was the mask, and then the full unmasked image. And I needed the masked image. In the end, I think it came out GREAT. For fun, here it is:

That’s my wife’s extended family. That piece is huge (relatively speaking) at 16" x 12" x .75". Took cutting the image in half and two 2-hour runs to get it on there. My sister-in-law is having me go completely insane make several smaller portraits that she’s going to hang off of this main one to make a sort of hanging family tree. With her cousins having some 10" x 6" ovals with their portraits, then their kids will hang off of those in little 4" x 5.5" ovals. I must admit, it’s an ambitious project for me. Especially since I haven’t even attempted a photo in over a year and a half (tried one as a first-week project and never tried again). But the vision is quite something. I hope the result lives up to it! :slight_smile:


I get that. I was thinking that might be the case…and I was also thinking that you probably already knew about the dismiss/ignore thing. Very nice image you got there…and especially after having a hiatus from working with photos. You’ve raised your own bar! Good work, Tom.


Cool! I like how it gives the photo an old-timey, vintage feel. Scary to do such a big engrave and you really nailed it!


I am amazed at the amount of detail that is on everyone’s faces. That is a great picture. :grin:


I was thinking the same thing. Honestly, I don’t see the appeal of lasered photos. Don’t worry, I realize that I’m pretty much the only one. :slight_smile: But I must say, with the old-timeyness that you observed I really dig it.

So was I! I totally just followed the official Glowforge tutorial. I was pretty blown away by the facial details.

Naw, you aint the only one. I don’t normally appreciate the look of the wood grain in most pics, but it does make for a nice rustic look. You did a great job with this (as always :slight_smile: ).


How about PhotoShop just erase the corners? Select a round eraser shape and size to get the radius you want, and center it at the corner of the photo and click. Set hardness up (to 100?) if you want a really sharp ‘cut’ line.

Thanks. Sure. I tried to do that. But I couldn’t figure out a way to center the selection on the corners. Is there a way to set the coordinates of a selection? I tried to figure it out for a minute this morning when I was working on it, but I quickly gave up on that one.

That’s the thing. Illustrator/Inkscape are designed for precision work, it’s possible to do it in PS, but the right tool makes every job easier. Clipping masks and rasterizing is the way to go.

If GF ever supports masks the workflow will get a bit simpler, but your guess is as good as mine there.

1 Like

An easy way is to fix the original photo as a layer in Gimp or what you are good with and make that pure white. In inkscape I use the clipping path but just to help center the image and the GFUI complains, but as it will not engrave there anyway i can ignore that,