Dots around my images

Hi! I just starting having an issue where little dots are showing up around my images.
I created them in Corel Draw. Some are text, Vector and Bitmaps that are exported as an svg before importing into the Glowforge. I’m getting dots around all them and I know they were not there when I created the artwork. See the pic.

What am I doing wrong?

The spots are most likely jpg artifacts. :grinning:


I agree with @davidgal2. It’s caused by JPG image compression. If you save your bitmaps as PNG instead, you shouldn’t get them. If you’re using images from another source and not ones you created yourself, you’ll have to just erase them out of the background, making sure it’s all pure white and not just something really close to white. :wink:


Ok so I saved the Vector images as a png. and you can see there are no artifacts.
See photo 1

When I upload into the glowforge now the dots are on the INSIDE of the image (whereas before they were on the outside)

I can’t clean up the file when there are no artifacts until I upload them. I’m at a loss…

I can’t see what you’re referring to in those low-res images, but I’ve been working with jpeg for 25 years and have never seen “artifacts” magically appear in solid areas other than directly adjacent the edges of shapes, which can be controlled with image quality settings if needed. The encoding of jpeg does not introduce random content in solid areas. If it did, high quality photographs would look terrible.

I use jpeg almost exclusively for raster on the GF and it doesn’t introduce random dots either. It takes a clean image and engraves just what’s there. The only reason I might use a png if if the source is already in that format, or it’s from a screenshot (png is the default format.)

If the empty space around your image is in fact not empty, and has random pixels that are even 1 level above empty, that would cause issues like what you are seeing. You have to manually erase everything around a shape to ensure there is nothing there. That’s where I spend a lot of time when working with images from sources other than my own.

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Sometimes artifact are nearly impossible to see with the naked eye. I have to zoom way in to see them…so perhaps that’s what’s happening here.

If those are Photo Engraves on raster style images, the dots are how the image is created…it’s called dithering. Various shades of gray are created by spacing the dots different amounts. It fools the eye into seeing gray instead of black and white from a distance. (A PNG file is a raster file format. Not vector.)

I am zooming in at 800% and don’t see any artifacts. They are vector images in Corel draw that I created. I’ve tried export as jpg, png and svg and am getting random dots (sometimes inside and sometimes outside of the images). Also on two occasions now when I uploaded them to the glowforge for a 2nd time they show up with no artifacts.

It feels like a glowforge problem to me since the artifacts appear inside or outside or not at all

Is that possible?

The implication here is that your image is not truly black and white. I went ahead and opened your png in gimp and used the dropper to pull what color the “black” actually is, and got this:

The color code is #363334 which is a quite dark almost pure grey. To get no dots at all, you need it to be solid black, #000000, which is pretty easy to do in most graphics programs.

I decided to help you out this time in case you don’t know how to do that, but next time you’ll want to learn how to do it on your own.

Right-click here to download this black and white pic.


thanks for all your replies. I really appreciate them .

Ok I get dithering. However there is no background around the vectors. Does the conversion to jpg or png or svg create that background?

And why would the ditheribg switch from the area around the image (background) to inside the image itself at random when I upload to the glowforge?

That image you are looking at is a screenshot and not the original. In Corel the file is pure black

If the color on the inside of the cartridge is even one point off of Pure White, the Glowforge interface will interpret it as a color and throw a few low power dots in there when it dithers. Usually those are not even enough to make it through the masking though…just run the sample engrave and see how it turns out.

(The dithering is different from the compression artifacts that you get when compressing a JPG image. Those are usually pixels of white that are a few points off of pure white - you can’t see them with your eyes, but the computer can. It will pick those up and engrave them.)

Make sure all white pixels are pure white if you want them to not show up as an engrave in the screen view, but they probably aren’t going to show in the final engraving, so give it a try.

Since you are using corel draw, try selecting your object, then clicking on View, then looking at the image using Simple wireframe. This should show you any dots in your image that you have not been able to see. Now you can remove the ones that you want. :blush:

Thanks everyone! I’ll try all the stuff you mentioned

You can also draw a box, light blue fill and send to the back of the page. You should see any dots show up on the light blue background.

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You might check your document workspace to make sure that’s it’s RGB. If you have a CMYK workspace set up, blacks can differ depending on how your preferences are set up (rich black vs true black for both display and output). Also, most programs won’t export out SVGs with CMYK declarations either, so it’s going to decide how to render the colors for you. This often isn’t a problem - until you run into not exactly white or not exactly black :slight_smile:

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