Working With Photographs on Your Laser in CorelDraw

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 arethree characteristics that we need toconsider

1 The first is how well does the material that we are working with hold a small well formed laser dot2 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 anodizedaluminum, 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 dotand are very porous. Thus photos do not look as goodon this medium

Product such as glass do not hold a good small dot and arevery porous. Thus photos so not look as good on thismedium

What this means is thatwhen we process a photowe need to establish firstwhat type of material thatwe are going to laser on.Once we have our materialwe 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

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 Toning2 -Error Diffusion

Our Number 2 Rule1- Half Toning – Fine Materials2 -Error Diffusion – CoarseMaterials

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 halftoneimage

Products that typically requirecontinuous tonal image – FineMaterials Anodized Aluminum Black Brass Coated Steel Laserable Plastic Some Marbles Laser It

Half Tones which the laser producesare Better on Anodized Aluminum orBrass 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 onwood

Products that typically requireerror diffusion  Wood  Thermark Product  Glass  Marble / Granite

Thermark on a Tile does not hold a good dotcompared to anodized aluminum thus we use anerror diffusion

Glass does not hold a good dot compared to anodizedaluminum thus we use an error diffusion

The quality of our image cangreatly influence our final product.

Thus we need to establishwhat is a good photographthat we can use

We need a Good QualityImage. The worse the imagequality the more chances wehave of not being able toreproduce the proper image

Original Image – Tif NoCompressions

Original Image Engraved

100 % Jpeg Quality

100 Percent jpeg

70 % Quality Jpeg

Other Bad Photos

Low Resolution and to dark

Low Resolution andBackground

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 tograyscale

Cropping to Size usingPowerClip

 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 BitmapMenu

3 areas pixel types in our TonalRange

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 certainpixels

Dark Adjustment

Light Adjustment

Contrast Enhancement

Contrast Enhancement box

Contrast Enhancement

Areas to look for when we areadjusting

Original

Minor Adjustment

Finished Product

Major Adjustment

Finished Product

Finished Product Engraved Dark Medium Lightestlittle adjustment medium adjustment Big Adjustment

If you are lasering on black brass orblack anodized aluminum you willneed to invert the image so that is is anegative.

 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 EngravePorous or Course Material likeWood and Glass we need to doan extra adjustment to ourphotoWe need use an error diffusionpattern

Different Diffusion Patterns

Error Diffusion Pattern createdon Glass

How do we create an errordiffusion on our original image

Convert our image inCorelDraw

Our photo converted to black andwhite 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 DialogueBox

I have increased the tonal range of the photo Original Adjusted

Now the question as to how much I adjust isdependent on what I am putting the image on.If I am going onto metal or plastic I would do alighter adjustment as I can show more detailon this material. If I am going onto wood Iwould use a more drastic adjustment

So the rule of thumb is more detail in yourimage if you are going to go on good materialsuch as laser brass. This is because I amgoing to use the halftone image to print myphoto. Thus I use a smaller adjustment in thecontrast enhancement commandIf I am going on a porous product such aswood I need to get rid of detail. Thus I woulddo larger adjustment in the contrastenhancement command

Remember that the worse (the moreporous) the material that we are workingon the more that we have to removedetail, Thus the better the material theless detail that we need to remove in thephoto

Now the secret step - Unsharp Mask

This technique is used all the time inprinting colour photographs becausemore photos are digital and they sufferfrom some sort of fuzziness. TheUnsharp mask will sharpen up thesephotos. I use this technique because itnot only does it sharpens up my imagebut it gets rid of some of the detail that Ican not produce. Thus the more detailthat I can not produce the more I use theUnsharp mask

Adjust the Percentage and Radius

For laser engraving on metal Iadjust the percentage to around200. For porous material I use 500and than adjust the radius to suite.

Our Image Sharpened

Now if I was going to laserengrave a fine material I wouldnow send it to the lasermachine.If I am going to a porousmaterial I need to do one extrastep

For our porous material we need to convert to Blackand White and use our Error Diffusion command

Use the Floyd SteinbergPattern

Here is your finished image

Our Image is ready to beLasered

Our Photo Lasered on Wood

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Working With Photographs on Your Laser in CorelDraw

by Mike Clarke on Feb 21, 2011

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Working With Photographs on Your Laser in CorelDraw — Presentation Transcript