This is the second part of my tutorial on lasering photos onto glass. This example came from a seminar I did with come of my customers. This photo is approximately 50 years old. We had to get rid of some creases to get it looking at least good enough for the laser machine.
Select Contrast Enhancement
Now that we have removed the background it is time to adjust out image. We are back in CorelDraw and our image has a transparent background thanks to use using the cutout lab in Corel PhotoPaint
Make Sure These Settings are Set
When you are in the contrast enhancement command you need to make sure that some settings are set. First of all make sure that the preview window is selected so we can see the before and after images (1). The original window is on the left (2). The preview window is on the right (3). Select the Lock button (4) to engage the preview. Click reset so that any presets we used before are cleared (5). The histogram (6) indicates our spatial concentration of pixels in our image. The dark pixels are on the left and the white pixels are on the right. Our adjustment sliders are the triangles above the histogram. The left slider (7) creates more darker contrast. The right slider (8) creates more contrast to the white. The gamma adjustment (9) shifts the entire image either lighter or darker.
Use the Contrast Enhancement Command
I adjust the two sliders inwards to increase the contrast of the image. It is very important usually on any photo to increase the contrast as this increases the chances of creating a good looking photo. What I am looking to do typically is to create some white in the traditional areas of the photo that are blown out by a flash or any light. These are highlighted by the red circles in the original image. The preview image is on the right. Note: because we are doing this photo on glass (or black granite) the image needs to be inverted. Because of this what is white becomes black and black becomes white. Typically for 99% of the photos I do I need to lighten the image up. Thus because I have to invert the photo the image has to be darker when I adjust. This is so important to remember. In this case I am doing the exact opposite if I was doing the image on wood. But remember you still need to create more contrast. I have done this in the photo. There are good white areas and good dark areas. Typically on a wood image I would not do much adjustment to the dark area of the photo.
Use the Unsharp Mask
Go to BITMAP | SHARPEN (1) | UNSHARP MASK (2)
Unsharp Mask Command
Typically I use a Percentage of 500 (1) when I am doing glass or wood or granite. The Radius will number in this case is 4 (2) but you need to adjust this one according to the photo that you are using.
Convert to Black and White
The next step is to select BITMAP (1) | MODE (2) | BLACK AND WHITE (3).
Select an Error Diffusion
Select one of the 3 error diffusion settings. Jarvis, Stucki or Floyd Steinburg. All three are fine.
Choose Floyd Steinburg
I have chosen Floyd Steinburg. The only other adjustment is the intensity slider. You can choose this to change the spacing of the dots.
My Finished Image
Here is my finished image. Now all we have to do is invert it. Did not take a lot of time and now I see exactly what I want and it costs me nothing.
Invert the Image
To Invert the image select EFFECTS (1) | TRANSFORM (2) | INVERT (3).
Our Image is Inverted
Here is the Finished Product
Hopefully as you can see the photograph has lasered quite well on the glass. Note: The one thing that you have to remember is that you need to mask the glass. For a further explanation on this technique visit my Lasering Glass Video.
Here is the Image Pictured From Behind
Here is the photograph pictured from behind as I look through the glass
Here is Another Picture
Just to make sure that I am not not using a good image here is another one