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Working With Photographs on Your Laser in CorelDraw

The document discusses best practices for laser engraving photos onto different materials. It explains that materials need to hold small dots well to look good, and lists anodized aluminum and laserable plastic as good options. Photos work best in grayscale or black and white. For fine materials that hold dots, like metal, half-toning is best to simulate continuous tone. For coarse materials like wood, error diffusion patterns are better. Good photos are high resolution with no compression. Contrast enhancement and unsharp masking can prepare photos for different materials by increasing or decreasing detail as needed. Converting to black and white with an error diffusion pattern is the final step for coarse materials.

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Objectives  What makes a good material  Diffusion patterns versus line screening (gray scaling)  What makes a good photo  Initial Prep on the Photo – what makes a good photo  Contrast Enhancement  Sharpening the secret to success  CorelDraw vsPhotoGRAVvs 1 Touch  Invert  Vignette  Cutout Lab in PhotoPaint
6 rules of lasering photo  Always work in Gray scale (a continuous tone image) or Black and white this depends on the material you are going to laser on  Know your materials that you want to work on  Make sure that you know your speeds and powers  Work only with good photos which shows only the focus no background images  Know your adjustment commands  Crop to Focus
What makes a good laserable material
When we look at materials there are three characteristics that we need to consider
1 The first is how well does the material that we are working with hold a small well formed laser dot 2 Secondly how well does that material display our image. In other word do we see good contrast. Is there a good difference in colour between the colour of the lasered and non lasered area. For example the best contrast is black and white. 3 The third is how good is the material in terms of being consistent. Wood is not good because it has a changing grain, anodized aluminum is very good because it has no grain
Products that hold a dot well are anodized aluminum, laserable plastic or brass plated steel
AlumaMark holds a half decent black dot - Gold
AlumaMark holds a half decent black - Silver
Product such as wood do not hold a good small dot and are very porous. Thus photos do not look as good on this medium
Product such as glass do not hold a good small dot and are very porous. Thus photos so not look as good on this medium
What this means is that when we process a photo we need to establish first what type of material that we are going to laser on. Once we have our material we can process the image
Before we go on let us look at the 3 main special programs for photo processing  ULS – One Touch  PhotoGrav  PhotoLaser
One Touch vs CorelDraw
One Touch vs CorelDraw
Corel vs One Touch
The Ultimate Photo
Our Number 1 Rule Thus materials that hold a good small dot need to be processed one way while those materials that do not hold a good dot need to be processed a different way Let us look at the two ways we can process an image.
Our two printing methods are: 1- Half Toning 2 -Error Diffusion
Our Number 2 Rule 1- Half Toning – Fine Materials 2 -Error Diffusion – Coarse Materials
Halftone and Error Diffusion
Half toning - Definition  Halftone is the reprographic technique that simulates continuous tone imagery through the use of dots, varying either in size, in shape or in spacing. "Halftone" can also be used to refer specifically to the image that is produced by this process. Where continuous tone imagery contains an infinite range of colors or grays, the halftone process reduces visual reproductions to a binary image that is printed with only one color of ink. This binary reproduction relies on a basic optical illusion that these tiny halftone dots are blended into smooth tones by the human eye.
Halftone Image – Continuous Tone Image
How Halftone Dots Appear
Screen Pattern with a halftone image
Products that typically require continuous tonal image – Fine Materials  Anodized Aluminum  Black Brass Coated Steel  Laserable Plastic  Some Marbles  Laser It
Half Tones which the laser produces are Better on Anodized Aluminum or Brass Plated Steel
What is Error Diffusion?  There is a second set of dithering patterns and these are created using what is called an error diffusion algorithm. These use a technique of diffusing quantization error to neighbouring pixels. Ok let us not get to technical. All you need to understand is that there are a number of error diffusion techniques that are available. Which one that you use is up to you. In CorelDraw we have 3 error diffusion algorithm patterns available to us. These are “Floyd- Steinberg”, “Jarvis” and “Stucki”. Others are “Burkes”, “Scolorq”, “Sierra”, “Atkinson” and “Filter Lite”. Figure 2 and 3 shows some of the more popular patterns that are available to use.
Error Diffusion - Patterns
Diffusion Patterns are better on wood
Products that typically require error diffusion  Wood  Thermark Product  Glass  Marble / Granite
Thermark on a Tile does not hold a good dot compared to anodized aluminum thus we use an error diffusion
Glass does not hold a good dot compared to anodized aluminum thus we use an error diffusion
The quality of our image can greatly influence our final product.
Thus we need to establish what is a good photograph that we can use
We need a Good Quality Image. The worse the image quality the more chances we have of not being able to reproduce the proper image
Original Image – Tif No Compressions
Original Image Engraved
100 % Jpeg Quality
100 Percent jpeg
70 % Quality Jpeg
70 % Quality Jpeg
Other Bad Photos
Low Resolution and to dark
Low Resolution and Background
Let Us Take a Close Look
Here is the finished photo
Best Photos Formats to get  Tiff or BMP are the best as long as they are not jpeg’s just saved as this format  Jpeg is the next best but remember JPEG can comes in a lot of different qualities  You may get a PDF but the original file may contain bad quality images
Converting to Grayscale
Working in Gray Scale
Image converted to grayscale
Cropping to Size using PowerClip
 Once we have converted the image to grayscale we will now need to process it to laser engrave it.  The Contrast Enhancement Dialogue box allows us to increase the tonal range of the photo that we are working on  To do this open up the Contrast Enhancement Dialogue Box
It is located in the Bitmap Menu
3 areas pixel types in our Tonal Range
What is Tonal Range  When we talk about the tonal range of an image we are referring to the range of tones between the lightest and darkest areas of an image. For example, an image with a wide tonal range will include both dark and light areas (and a range of tones in between). Whereas an image with a narrow tonal range will cover a more restricted range for example it could be predominantly composed of mid-tones. Note: when we look at an image that is a grayscale image we have an image that is comprised of gray pixels that have a value of 0 to 255. Values that are 0 are solid black and values that are 255 are solid white. Pixels with a number in between 0 and 255 are a shade of gray.
Each slider adjusts certain pixels
Dark Adjustment
Light Adjustment
Contrast Enhancement
Contrast Enhancement box
Contrast Enhancement
Areas to look for when we are adjusting
Original
Minor Adjustment
Finished Product
Major Adjustment
Finished Product
Finished Product Engraved Dark Medium Lightest little adjustment medium adjustment Big Adjustment
If you are lasering on black brass or black anodized aluminum you will need to invert the image so that is is a negative.
 We have worked with photos that would traditionally be laser engraved on good material such as laser brass or anodized aluminum. But what about wood, glass and granite?  To engrave this material we use what is called the error diffusion technique
To Successfully Laser Engrave Porous or Course Material like Wood and Glass we need to do an extra adjustment to our photo We need use an error diffusion pattern
Different Diffusion Patterns
Error Diffusion Pattern created on Glass
How do we create an error diffusion on our original image
Convert our image in CorelDraw
Our photo converted to black and white with an error diffusion pattern
The Holy Grail for Doing Photos In CorelDraw
Our Original Image
First convert the photo to Grayscale
Open the Contrast Enhancement Dialogue Box
I have increased the tonal range of the photo Original Adjusted
Now the question as to how much I adjust is dependent on what I am putting the image on. If I am going onto metal or plastic I would do a lighter adjustment as I can show more detail on this material. If I am going onto wood I would use a more drastic adjustment
So the rule of thumb is more detail in your image if you are going to go on good material such as laser brass. This is because I am going to use the halftone image to print my photo. Thus I use a smaller adjustment in the contrast enhancement command If I am going on a porous product such as wood I need to get rid of detail. Thus I would do larger adjustment in the contrast enhancement command
Remember that the worse (the more porous) the material that we are working on the more that we have to remove detail, Thus the better the material the less detail that we need to remove in the photo
Now the secret step - Unsharp Mask
This technique is used all the time in printing colour photographs because more photos are digital and they suffer from some sort of fuzziness. The Unsharp mask will sharpen up these photos. I use this technique because it not only does it sharpens up my image but it gets rid of some of the detail that I can not produce. Thus the more detail that I can not produce the more I use the Unsharp mask
Adjust the Percentage and Radius
For laser engraving on metal I adjust the percentage to around 200. For porous material I use 500 and than adjust the radius to suite.
Our Image Sharpened
Now if I was going to laser engrave a fine material I would now send it to the laser machine. If I am going to a porous material I need to do one extra step
For our porous material we need to convert to Black and White and use our Error Diffusion command
Use the Floyd Steinberg Pattern