Glowforge Projects: Glowforge Photo Engrave Using Photoshop

Glowforge Photo Engraving

A Glowforge Project

If you're here, you probably have a Glowforge project in mind for engraving a picture and are wondering the best way to do it. And you're in the right place. Besides cutting jigsaw puzzles, laser engraving photos keeps my machine pretty busy.

This is a complete walkthrough of how I prepare images for laser photo engraving. 

Laser engraving pictures is not without challenges! In fact, it sometimes seems like despite it being one of the most popular laser cutting ideas and Glowforge projects, there is a fair amount of the unknown surrounding the topic. 

Laser Photo Engraving Philosophy

Much like the Instant Pot recipe you may be looking up next because you need an easy meal for the family since you're so busy lasering, laser engraving photos is a lot like a recipe and making a dish.

The way you edit your photo and the engraving material you choose (the ingredients), must come together with the right engraving settings such as power, speed, and resolution (the cook-time and temperature).

What This Laser Engraving Guide is About

I am going to take you on a walkthrough of the process involved in editing a photo for engraving on your laser and knocking that Glowforge project out of the sky.

I use Adobe Photoshop, but much of the process can be adapted to other programs like Affinity Photo (which has many of the same tools as Photoshop) and Gimp. The tools do have different names in different programs, but they are generally close enough that you can figure it out. 

(PS. If you don't have a subscription to Photoshop yet, the plan to get is the Photographers Package, which includes Lightroom and Photoshop for $9.99/month - definitely the best deal! I'm an authorized Adobe affiliate, and this link will take you straight to that awesome plan.)

When I first started editing photos for laser engraving, I found that I was having to do the same thing over and over. When I wanted to make a change, I'd have to start over because the edits had already been committed to the source image. Annoying! It felt like a personal version of that movie, Groundhog Day.

To remedy this, I put together a series of laser engraving Photoshop actions that automated the process of putting all of my tools into one place, made some pretty good guesses at the edits needed, and allowed all of the customizations I wanted and needed.

Those actions kind of took on a life of their own as I had more ideas: creating cut lines automatically, exporting into a custom PDF so that the Glowforge app didn't resize high-resolution pictures, test burns, and more.

If you find this editing process of value but get tired of running through the motions, consider checking out the Photoshop actions. They make my editing time much more efficient. And efficiency is dollars. The actions pay for themselves in a little as 1 or 2 engraves. This is how you make Glowforge projects make money.

Here is a picture of Rio for you to download so you participate in the play by play:

Download Rio_Dog-Days-of-Summer.jpg (Right-click and Save)

Image Preparation Steps for Laser Engraving a Photo

Step 1, Loading Your Image:

Load your hi-resolution image into Photoshop and double-click the background layer to make it an editable layer. Then, we will right-click on this layer and make it a "Smart Object."

Step 2, Black and White Adjustment Layer:

Create a new Black and White adjustment layer. I've already created the adjustment layer here, and it can be seen in the background behind the adjustment layer menu.

Creating an adjustment layer allows you to non-destructively edit or make changes to your image so that you can adjust as needed.
The Black and White mixer is a potent tool! It will allow us to modify how the color values are translated into black and white. To adjust how these colors are mixed, double click the layer thumbnail, which is the small square that is black and transparent.

Double-clicking the layer thumbnail will open the properties dialog, where we can adjust how the colors are mixed. The values that we will change will depend on the colors in the image and what we want, either light or dark.

Here's an example of how Rio changes when I modify how the color Red is mixed. The image on the left shows the red slider at 0. The image on the right shows the red slider at 88. Increasing the slider value lightens the colors that have red in them. Decreasing the slider value darkens the colors that have red in them.

Going through each color available in the mix, you can modify the image to your liking. This example of Rio has a little bit of all colors (which is why I picked it - besides him being a pretty good lookin' pup).

By increasing the green slider, I can push the green foliage up so that it will engrave lighter. Also, a small amount of blues and cyans were picked up in his fur. By increasing these values, I get more detail out of his dark coat.

Pro-tip: If there is a particular area that you want to modify directly, you can choose the eyedropper tool in the black and white adjustment palette and it will modify all of the colors that make up the sample area. 

My final Black and White settings for Rio look like this:

 

Step 3, Brightness / Contrast Adjustment Layer:

Create a Brightness / Contrast Adjustment Layer.

I tend to keep these settings in the mid 20's. They don't drastically change an image but create subtle changes that help to lighten the overall image and increase contrast.

 

Step 4, Levels Adjustment Layer: 

Make a Levels adjustment layer.

Levels are a tool that can stretch and move the levels of brightness in an image based on the shadows, mid-tones, and highlights. It's a little more complex than that, but we're not trying to write a book about Photoshop here - just how to laser engrave your image!

The levels adjustment tool will have 3 sliders. The slider on the left controls the brightness levels for the darker areas of the image. The middle slider controls the mid-tones, and the right slider controls the brightness in the highlights of the image. These will default to values of 0 (dark areas), 1.0 (mid-tones), and 255 (highlights).

For this image of Rio, I slid the left/dark slider to the right just a bit, I slid the mid-tones to the left just a bit, and I left the right slider/highlights alone. This helped to "push" the shadows up. Thus creating detail and contrast in the mid-tones and left the highlights alone.

 

Step 5, Shadows and Highlights Layer:

Create a shadows and highlights smart layer.

We will click on our source image layer to select it, then go to Image > Adjustments > Shadow / Highlights.

This is a potent tool that can extract a lot of detail from both the shadows and highlight regions of your photos. This ultimately creates contrast making your engraving more realistic and exciting - seemingly popping off of the wood or other material.

To edit the highlights and shadows for Rio, I did the following:

Shadows:
Amount: 15% (the total correct desired, or how much I'm going to push the shadows up)
Tone: 24% (how broad of a range in the shadows I want to be selected - a higher percentage increases the number of dark areas affected)
Radius: 28 pixels (determines how large of a radius in pixels is affected by the adjustment)

Highlights:
Amount: 14%
Tone: 50%
Radius: 30 pixels

These settings allowed me to pull the highlights down, creating a lot of texture and detail in the white areas of his coat. It also pushed the dark places of his coat up, creating more texture that we will see in the engraving.

 

Step 6, Resize Your Image for Engraving:

Resize your image to the desired engrave size. Here, I generally copy all of the edits into a brand new file which leaves my original source image completely editable. This is part of what my actions do. :)

To resize, click Image > Image Resize

Without getting into all of the fancy details about resolution, image size, Photoshop, and 72 PPI - you can see this is a big, high-resolution image. We want to scale it down and increase the pixels per inch to get to a final engravable image.

I make sure that my "resample box" is checked, as well as the "anchor link" between the width and height (this keeps the image from getting all stretched out funny). I know that I'll want to engrave this image at 7" wide, so I change the width to 7". The resolution is a debatable topic. Some insist that it must match the resolution/lines per inch you will be engraving at. Generally, this will be at 270 or higher. One thing is for absolute - you do not want it to be less than the resolution than you are engraving it at!

 

Step 7, Sharpen:

Sharpen! Photographers that are engraving photos will hate this step. I did.

To create our sharpening effect, we will again click our source image layer, go to the menu and perform Filter > Sharpen > Smart Sharpen

Why do photographers hate this? All images are sharpened for printing, so we have a pretty good idea of what the sharpened photo should look like. Laser engraving a photo requires sharpening the image beyond what you would sharpen it for inkjet printing but less than the point where you say what the hell just happened?

A lot of recommendations say to just max out the sharpness. I don't like this. Doing this creates halos around the subjects in your engraving and doesn't look good.

I tend to like values around what is depicted in the below screenshot. In the 200%'ish range for the amount of sharpening, around 2.5 to 3.5 in pixels affected. I also like to reduce the noise by about 15-25%, which smooths things out just a touch.

Step 8, Save and Print: 

Save and Print.

Another thing that I figured out with my actions was how to save the image as a PDF that respected the Pixels Per Inch (PPI / Resolution) value that I set earlier. It involved a lot of custom settings... For now, though, we can just Save As a Glowforge acceptable format (PDF, JPG, PNG).

When imported, it will come in too big and will need to be scaled back down. This is normal and a function of the web interface.

Our other (preferred) option is to import the image into a program like Inkscape or Illustrator. We can embed the image into an SVG or PDF file in those programs, where it will save and respect the resolution.

Laser Engraving Conclusions

For comparison, here is what we started with and what we ended with:

If this seems like a fair amount of work, well, it is. But, it's also the best way to get edits specific to your image and not just good guesses. Every image doesn't need this level of attention, but a lot do.

Make Laser Engraving Easier and Faster?

If you're interested, check out my Photoshop Actions - which do all of these steps with pretty much the click of a button - and a lot more.

If you don't own a Glowforge yet and want to buy your own, this referral link will save you $100-500, and put a little cash back in my pocket. 

Update 5/2021:

Despite this being written for a Glowforge, I use this process everyday for photo engraving with both my Trotec Speedy 400 and Universal Laser Systems VLS460. I know many others use it for their Aeon Mira and Thunders that operate using Lightburn. Some slight differences may be needed on the laser end. For example, if processing an image in this way for a Trotec Laser System, I would recommend not using the Photo Optimized mode.