You have asked:

Icefields and the counting of tonal levels

Why does Icefields require input of tonal values expressed as numbers between 0 and 255?

Accuracy and familiarity are the important reasons.

8-bit or 1 byte is a common method of encoding values in a computer. There are 256 values in 1 byte. Percentages expressed in integers result in only 100 values and are not accurate. Decimal equivalents between 0 and 1 are occasionally not real numbers.  the 127 value is ~0.49609375. (Icefields internally converts integers to the closest floats in1 byte binary hence rounding errors seldom occur and 16-bit calculations are not necessary.)

Why does Icefields require halftone and device resolutions expressed infrequency of dots and not in diameter of dots?

Familiarity, consistency, common usage, and variable dot diameter are important reasons.

Some RIP manufacturers require the user to input FM dots in the diameter they desire, expressed in microns, while AM dots are expressed in frequency. Since frequency is always the expression of device resolution, it is easier to calculate the FM resolution in frequency rather than convert a number of device dots in the FM cluster to a dot diameter.

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 yellow position
   

2. •Place 50% gray ink in the magenta 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 $450 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.
   

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
   

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.

Icefields is the only printer-independent software that manages your print workflow through halftoning. Icefields screens are used on offset, flexographic, silk-screen and rotogravure presses. Icefields screens are used for carbon and platinum photography.

An Icefields FM screen was first used for newspaper printing in 1996. Icefields screens are the most widely tested halftones available. Icefields is exclusively for the Apple Macintosh computer.