calibration

When producing a lenticular image it is critical that you know exactly how many lenses per inch (or cm or meters or furlongs) you lenticular sheet has. Not all lenticular sheets exactly match their stated LPI, and the same often applies to the printer. For this reason it is advisable to " Calibrate " your printer and lenticular sheet combination.

Lentikit provides two calibration tools: Tilt calibration and Bar calibration, described below.

Tilt Calibration

This is an experimental mechanism for calibration that may (for all I know) be unique to Lentikit. Tilt calibration is unusual in that it allows you to print out a test sheet that can be used for calibrating a number of different sheets on a single print.Unfortunately so far it is only crudely accurate, and Bar calibration is to be recommended for further refining the values gained from this step.

To use Tilt Calibration, bring up the tilt calibration tool from the tools menu, it brings up the lean and miserable dialog you can see to the left.

You can specify the size of the output in pixels, the target DPI, and the nominal LPI's you want to calibrate. You will get an output similar to:

Click for full size image

Notice that an extra band is printed for slightly less than each nominal LPI, this is because tilt calibration can o nly work for LPI's that are greater than the nominal, and printing a band for 0.5 lpi less should guarantee this.

To use this to calibrate: Place your sheet so the left edge passes precisely though the cross. Then tilt the sheet clockwise until perfectly horizontal black lines are seen in the target band. Again check the left edge goes through the cross, and read a multiply factor from where the edge of the sheet crosses the tick marks. This number will be between 1.000 and 1.025. For example, my sheet is approx 75 LPI, I can get horizontal lines on the 75 bar, and the tilt value is at the fifth tick - i.e. 1.005. This tells me my effective LPI (at least for this printer) is 75*1.005 = 75.375. In my case I can also get a tilt calibration to work on the 74.5 bar - a value of: 12 ticks - 1.012 * 74.5 = 75.394. So I can guess that my sheet is probably between 75.35 and 75.45 LPI. And this is what I will use in the next step: Bar Calibration

Bar Calibration

This is a more conventional mechanism for calibration. You specify a nominal LPI for your sheet, and get Lentikit to produce a test sheet that has several bars at intervals around the nominal LPI. You then place your sheet over the prnitout and the bar that displays all black is the actual LPI combination for that sheet and printer. All quite simple really.