1. Open Image in Photoshop. Adjust contrast as needed.

2. Change the image to grayscale. (Image>Mode>Grayscale>Discard)

3. Adjust the image to 300 dpi to produce rounded dots. Lower dpi will produce dots with sharper edges. (Image>Image Size>Resolution)

4. Image>Mode>BitmapFor relief printing the image produced for the laser cutter should have a lower lpi fre-quency, no higher than 72 lpi on hardwood. A higher lpi will create an image that aes-thetically matches the computer but cannot be relief rolled as the laser will recut pixels over previous cuts.

5. The laser will not read a bitmap image, the image must be returned to grayscale. (Image>Mode>Grayscale>Size Ratio: 1)

6. Use the marquee tool to draw a small 1” x 1” square, copy and paste to a new Ado-be photoshop file. Cut this small 1” file as a test on scrap material to see that the laser cutter will cut the file with the correct depth.

7. Save the file as a .jpeg or .psd and import into the Illustrator cutting template from the mpf.aap.cornell.edu website.

Do not live trace the file, as long as it is saved in grayscale, it will cut.

The file will cut only in the black setting. In the laser cutter print>setup>preferences box, adjust the file settings to raster/vector. Your file will cut slowly as a raster file.

Estimated time:6” x 6” = 30 minutes cutting time.

PHOTOSHOP BITMAP METHODS

2.

4.

Method One: Photoshop Bitmap

J.Scheuer 2016

50% Threshold – splits the grayscale in half to produce pixels white or black. Adjust brightness and contrast to alternate the appearance of the bitmap threshold result. Reduce the output resolution to below 72 for lasercutting.

Diffusion Dither – divides the image to individual pixels that are white or black. Pixel size must be less than 72 dpi for the laser cutter to produce the image, alternately the laser will cut into the materi-al with each pass that removes some of the previous pixels.

Halftone Screen – produces user defined dots to produce tonal image in black

Output Resolution: Changing the resolution produces a simplified image from source.

Halftone Screen Dialog Options:

Frequency – enter how many bitmap dots per inch to produce Angle – angles are intended to produce multiple colors, but screen angle affects how effec tively the bitmap shape is produced. CMYK printing requires different screen angles to reduce moire patterns (see suggestions below). Shape –(round, diamond, ellipse, line, square, cross, images are often ellipse/round are used) Try the following suggestions for producing a classic half-tone dot. Halftone screen> dpi 300 > Frequency (1-70), Angle: 22.5, Ellipse Halftone screen> dpi 300 > Frequency (1-70), Angle: 22.5, Round Halftone screen> dpi 720 > Frequency (1-70), Angle: 22.5 Ellipse

PHOTOSHOP BITMAP METHODSDefinitions and Adjusting Results For Method One

1. 2. 3. 4.

The images above illustrate different dpi input, dpi output, lpi frequency, and shapes. Experiment and adjust this information to vary results. Additionally, contrast will highly affect the results created with this bitmap method. These images were created with the following information:

Image 1: Input 720, Output 720, lpi 25, Ellipse Image 2: Input 720, Output 300, lpi 65, Ellipse Image 3: Input 720, Output 1500, lpi 25, Round Image 4: Input 720, Output 720, lpi 65, Line

J.Scheuer 2016

1. The image produced for the laser cutter should have pixels at no closer than 100 dpi, better <72dpi, but a lower dpi will produce a more reliable result. For the color halftone, the minimum pixel size input is four- so a resolution of 150-300 will work well to pro-duce an image with detail. Image>Image Size>adjust dpi.

2. Change the image to grayscale. (Image>Mode>Grayscale>Discard)

3. Adjust the brightness and contrast of the image to produce more information. (Image>Adjustments>Brightness/Contrast>{adjust}>ok)

4. Filter>Pixelate>Color Halftone Screen

5. Select the maximum radius of dot and screen angle for channel one only. (try 5-50)

6a. Zoom into the file and adjust the bright-ness and contrast to reduce grays.

7a. Create a bitmap threshold (Image>-Mode>Bitmap>Choose Output dpi and 50% Threshold)

8a. Image>Grayscale>Size Ratio 1

or

6b. Save and import into Illustrator

7b. Live Trace Options > Adjust threshold to 200-240, minimum area to 1, path to 1

8b. To produce outlines (for stencils) > Click Expand > Adjust line weight to .001 > Change fill to none > Change Color to Black

PHOTOSHOP BITMAP METHODS

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7a.

Method Two: Photoshop Color Halftone (B & W)

J.Scheuer 2016

PHOTOSHOP BITMAP METHODSColor Seperations & the Round Dots Method1. The image produced for the laser cutter should have pixels at 72 dpi or <72dpi, but a lower dpi will produce a more reliable result. Image>Image Size>Reduce to max 72 dpi. For screenprint, the image should be 1/5 of the mesh count (50-65 for our screens).

2. Change the image to CMYK.(Image>Mode>CMYK Color) (Layer>Rasterize>Flatten>Discard)

3. Open the channels Window to see the color separations. (Windows > Channels)

4. Use the filter to create the separations. (Filter>Pixelate>Color Halftone Screen)

5. Select the maximum radius of dot and screen angle for channel one only.

6. Change the color channels to reduce moire, try the following:

C105, M75, Y90, K45 or C15, M75, Y0, K45 or C80, M20, Y5, K50

7. In the Channel Menu >Split Channels

8. Repeat the B & W steps 6-8 for removing grays from the image Zoom into the file and adjust the brightness and contrast to reduce grays.

Create a bitmap threshold (Image Mode>Bitmap>Choose Output dpi and 50% Threshold)

Image>Grayscale>Size Ratio 1

Best method for Round Dots (Multiple Channels): IN PHOTOSHOP:

1. Image > Image Size > Reduce to lower dpi, 72 or less 2. Image > Mode > CMYK Color (Rasterize > Flatten > Discard) 3. Window > Channels 4. In the Channel Menu > Split Channels 5. Import Each file into a new Illustrator Document

IN ILLUSTRATOR:

1. Filter > Pixelate > Color Halftone Screen 2. Select Maximum Radius of Dot (How many Pixels per dot) 3. Change color channel to reduce moire (see above) 4. Live Trace > Tracing Options, Adjust Path- 1, Corner Angle- 5 5. Repeat for all colors

J.Scheuer 2016