Here is where the magic begins! In order to understand interlacing, it will help if you have a good degree of working knowledge with graphic programs, resolution factors, output devices, proofing methods, imagesetters, and offset litho printing. If you don't, you should work with a printing company that has a successful track record with lenticular printing.
The printer's equipment and its capabilities will play a huge roll in how you will need to interlace the art that they will proof and print. The printers proofing and plating devices have a defined output resolution, or target resolution.
Create or select art and/or images that are lenticular friendly. (Remember to review the DO's and DON'Ts section of this site prior to starting your project for suggestions.)
Select the correct lenticular lens for the planned effect being used-keeping in mind how your piece will be used and the distance in which it will be viewed at. Will it be hand-held like a business card or larger like a P.O.P. display? This is where you will find viewing distance to be a key issue. For more details, see LENTICULAR LENS PROPERTIES.
Find the visual pitch of your lens. Pitch-testing the lenticular lens to the proofing device will determine the proofing pitch. Each device can, and will, have a bit of variance. (This means you may see a slight difference between printers from the same manufacturer and even the same model type.) Note: Be sure to proof your work on the same printer that you performed the proofing pitchtest.
How to determine the visual pitch...
When moving your head from right to left (turn sheet so that the lens is vertically) you should notice the lower LPI bars will move in the opposite direction and the higher numbered LPI bars are moving in the same direction as you. These opposing movements should appear to come together where the visual pitch will be. In the example to right, this would be 101.5 lpi. The entire 101.5 bar, or most of it, is appearing to flip from black to clear.
Remember to run your pitch test at the planned viewing distance. Lets say that you find the 101.5 bar appearing to sweep ever-so-slightly to the left as you move to the right, and the 101.4 bar appears to sweep slightly to the right. You can make the determination that the pitch is in-between the two. You can fine tune a pitch to be at 1/1000s of an inch. The pitchtest form is graduated in 1/100s of an inch. If you are working with a press pitch in 1/1000s of an inch, the resizing formula remains the same. This is a critical step and the more accurate you are will result in a finer action on the final printed product.
Use a good color printer during the art-assembly stage. Proofing your own interlaced art is suggested. Keep in mind that having the printing company proof your art during the design phase can, and will, become very costly. You can create action proofs to assess your progress using your own equipment.
In order to do this, you will need to create a pitchtest form. (This should be included with your interlacing or lenticular software package.)
Lastly, you'll need to determine which direction the interlaced art and pitchtest should be outputted. Inkjet and bubble-jet printers all print a finer, more accurate, dot or resolution in the direction the print head travels. This is why you see the resolution of these types of printers to be something like 1440 x 720. The print head moves horizontally to write the image (the 1440 dpi.) The paper is driven through the printer vertically by a mechanical gear system (the 720 dpi.) The print heads fire on and off to image the sheet and are more precise than the drive mechanism moving the sheet through the device. Knowing this, you will need to position your art either "portrait" or "landscape" so that the print heads write the frequency of the LPI and NOT the length. Another good tip is to use the same high quality photo paper for the pitchtest as what will be used when you are ready to print your interlaced art to create the action proof.
