You have asked:

Why does the view of my quadtone, duotone, and under-color removal results look strange?

  1. You have prepared your image for print reproduction -- not for viewing on a monitor. The image data is in a CMYK color space but isn’t a true CMYK image. The monitor cannot transform the CMYK channels to an RGB colorspace correctly. For example the quadtone places four grayscale versions of an image into CMYK channels. There is currently no method to convert four grayscale images into one RGB color space.

What is the ink order for quadtone printing?

  1. •Place 25% gray ink in the black position

  2. •Place 50% gray ink in the yellow position

  3. •Place 75% gray ink in the cyan position

  4. •Place black ink in the black position

What are the advantages of FM halftones?

  1. •Reduces the amount of ink needed

  2. •Provides a larger gamut than traditional halftones

  3. •Eliminates moiré patterns

  4. •Displays greater detail

  5. •Distributes ink more evenly across the plate

  6. •Solves screen angle problems for touch plates

  7. •Simulates continuous tone photographs

  8. •Creates smoother gradients

  9. •Ink dries faster on the sheet

  10. •Provides a more consistent print run

What are the advantages of using Icefields?

  1. •Price: At $150 Icefields is very affordable

  2. •Speed: The graphics co-processor in your Macintosh makes it very fast

  3. •Quality: Considered to be one of the best -- sharpening neutral, smooth gradients, and much more

  4. •Proven capability: Icefields has been in use since 1995.

  5. •Portability: Makes halftone documents for off-site printers

  6. •Soft proofing: View the image before and after halftoning

  7. •Mix traditional halftoned and stochastic screened images on the same page

  8. •Control of dot-gain and resolution: Simple interface makes calibration and dot-size control easy

Is Icefields a raster image processor (RIP)?

  1. When you print from Icefields that’s exactly what it is -- a rip using the OS X driver. When you make a document for offsite printing then Icefields provides most of the rip functions offsite.

Is Icefields a 16-bit image processor?

  1. Icefields supports input of images in 16-bit and outputs 8-bit halftones. Icefields working bit-depth is 8-bit. There are several reasons why 16-bit only slows down the processing time with no increase in quality.

  2. 1.Icefields floating-point processing eliminates rounding errors.

  3. 2.Icefields error-handling cycles any numerical errors (numbers that lie between the 256 8-bit numbers) back into the calculations.

  4. 3.The greater dot frequency of the printer's resolution contains all the information that a greater amplitude (bit-depth) can contain. Data is not lost in the 16-bit to 8-bit compression.

Are there other sources for information about Icefields?

  1. Icefields’ off-site capability was used for samples of reproduction in the following trade texts:

  2. •Real World Scanning & Halftones, David Blatner, et., Peachpit Press

  3. •Making Digital Negatives for Contact Printing, Dan Burkholder, Bladed Iris Press

  4. •Preparing Digital Images for Print, Sybil & Emil Ihrig, Osborne McGraw-Hill Publishers

Will my printer re-screen Icefields documents?

  1. Probably not. Good cluster and diffusion dithers only screen tones other than black and white. That’s why your black type isn’t halftoned. A pixel-to-dot reproduction is faster and more accurate than making a halftone. Many Icefields users claim their printers fly with Icefields documents.

Are Icefields documents device-independent?

  1. Most documents are device independent -- not Icefields documents! Since the Icefields document contains the printer’s resolution and calibration, the document is dependent on that particular printer.

Is there anything in my workflow I should be cautious about?

  1. On some inkjet printers, Icefields improves the output quality, while on others it reduces the quality. It all depends on the rip or driver. If your inkjet printer drives only RGB images then Icefields’ documents look very strange. Changing from CMYK to RGB degrades quality.

Is Icefields a PDF-conforming RIP?

  1. No, Icefields does not conform to Adobe Systems Inc. halftone types, transfer functions, and color dictionary specifications. It provides its own halftones, the transfer function is part of the user interface, and ICC profiles are used for color space transformations.

What do the terms FM (frequency modulated), diffusion and stochastic mean?

  1. The simplest definition of an FM halftone is: a field of dots that modulate in distances from each other. The term halftone is defined by its context. Halftone is either the generic term for all bitmap fields produced on a printer, or a cluster of micro-dots occurring at regular intervals.

  2. All halftones describe a bitmap by the distance between dots (frequency) and by the size of each dot (amplitude). When amplitude receives the most processing time then that halftone is called a halftone. When the frequency receives most of the processing time then that halftone is labeled as FM, diffusion or stochastic. Many halftones combine frequency and amplitude processing times. These halftones are hard to name and are called by their trademark names or simply hybrids.