What is Calibration?

Calibration is the process of telling the Media Manager how your printer uses ink when specific demands for each color are given.  If the output matched the demand, then we could plot the results as a 1 to 1 graph.  Such a graph would be a straight line.  Thus the term "Linearization".

But just because we know how our printer is using ink, it doesn't mean we can get reproducible results from print to print or from day to day.  We need to use that information along with a set of targets.  If you were using a bow and arrow, you would need to know how far your arrow will go based on your strength and aiming abilities.  But in order to know you are really accurate you aim for a specific target.  When you hit the target you are at your peak of performance.  Tell Media Manager how much ink to use for each color across the range of color demands by setting your "Target Density" for your profiling purpose.  If we hit the same target densities from print to print and from day to day we will be achieving reproducibility.  Such reproducibility is the foundation of getting accurate results.

How to create a calibration table:

Calibration is preformed after setting Ink Restrictions and any Transition Controls (not needed for most media).  To begin the calibration process, make sure you have a densitometric color sampling device connected. See Densitometer. 

1. Click the Print Swatch button from the "Print and read the calibration swatch" dialog.  This opens a print dialog. 
2. Verify that the densitometric device that is plugged into your system is displayed in the Device box.  If not, click the drop down list and highlight your device. 
3. If you don't see your device you can click Setup > Measurement Device > Add to select your device from the list of supported densitometers. 
4. Once you have changed any Setup settings click > Print to send the swatch job to the print queue.

**NOTE** The default swatch prints 31 patches with a variance of approximately 3% per patch. There are a few scenarios when you may wish to change this options for the number of patches printed on the calibration swatch. For example: if your media is textured like a canvas or porous like a perforated vinyl, or if you are using a grand format printer you may get better results if you use fewer swatch patches for each color.  For example some printer manufactures such as HP/Scitex recommends 19 (4%) or 24 (5%) patches.

To change the number of patches before you print the calibration swatch:

1. Click > Setup > Options.
2. On the Options tab enter the desires value (either 19 or 24) in the field and you will see the % displayed to the right.
3. If you are confident that your printer has fairly linear output you can use fewer patches.  In some cases fewer patches will also result in readings that have fewer "spikes" in the readings.  Very rarely is there any advantage to be gained by using more than the default 31 patches per color and this is not recommended. Too much detail can result in profiling issues later on in the workflow.
4. Click > OK.
5. Click > Print. 
6. Once the swatches have had adequate Real World click > Read Swatches. 
7. Follow the instructions given for this step. Depending on the color sampling device you may be required to calibrate the device with the manufacturer's calibration swatch as well as taking an initial "white" reading on the media being profiled. 
8. Once the readings are complete click > OK to accept.
9. Click > Build to create the calibration table.

**NOTE**When you click > OK to accept the calibration readings, you'll may see a pop-up window with the options to manually edit or automatically correct for invalid readings. Invalid readings are usually numbers or numbers out of sequence with a regular tonal change. Basic users are encourages to click > Auto Edit which allows the software to correct the values. Advanced users may wish to review the values and make the changes manually. To do this use the following steps:

1. Click > Manually edit and locate the values you want to change.
2. Click your mouse into the field and remove the . Or take an average of the readings above and below to decide the approximate value.
3. You only need to be concerned with the numbers displayed in the column for the color channel shown on the left-hand side.
4. Once you have made your corrections click > Build to create the calibration table.  

The next step is to choose a Media Model which will use the calibration table to create a series of target densities from which a linearization curve is built.

Back to Profiling Step By Step.