Before interlacing it is necessary to determine the exact pitch of the lenticular sheet.

We will distinguish the visual pitch and the mechanical (or absolute) pitch.
To determine the visual pitch of the lenticular sheet, it is necessary to carry out a pitch test.
We can provide this file to our customers (free).
This file will be used to output a film or a plate.
It is possible to determine the pitch by placing a lenticular clear sheet on the plate (or the film) and look at the viewing distance of the final image.

One line will be totally black or invisible, it will be your visual pitch.
The result will be more precise if you print the pitch test on the lenticular sheets.

If, for example, the test shows that the optical pitch is 75,48 LPI, you will thus interlace 16 images in

The mechanical pitch will be determined using a magnifying glass.

Computer

You need a computer with a memory (RAM) minimum of 2 GB and a processor of at least 2 Ghz.
The lenticular files can become enormous, and the imposition, if it is not made in the RIP is very heavy for a workstation.

Software:

    1. Adobe Photoshop (see below how to interlace in Photoshop)
    2. Quark
    3. Adobe After Effects
    4. Adobe InDesign
    5. ArtPro
    6. Lenticular Software

 

 

 

A minimum of 300 lines per inch is essential for an acceptable quality, a higher quality can be obtained with 450-500 lines. Adapt linescreen to a value mathematically compatible with the pitch of the lens will produce a better result, this can also reduce or eliminate the banding caused by interpolation of the image when creating dots.
Specific screen angles must be used to avoid moiré. We can provide you this information.

The CTP (or CTF) must have a resolution of at least 2400 DPI, a higher resolution will give a better result. The majority of the current CTP have a capacity between 2400 to 4000 DPI, some can achieve higher resolution, they are mainly designed for safety printing.

The standard films have a thickness of 0,01mm, whereas 0,018 mm are recommended for a better stability of measurement. Note: when using 0,018 mm films, the laser heads should be recalibrated.
In the same way, when using high resolutions, the proper laser resolution intensity values should be established and setup, also exposure curves created, to produce linear reproduction of dot values.


We experienced that the 3M Imation match print system is working perfectly. It is very stable whereas others are expanding or retracting, requiring corrections. `Low Gain' paper is excellent, sometimes even better than the result on press.
It is also possible to test the effects using a high resolution inkjet printer (min 1440 PPI) but it will be necessary to adjust the pitch to this device as the pitch will be different from your CTP.
Some current CTP have a direct proofing system.


It is possible to interlace with only Photoshop by using the following procedure:

For a flip:
1)    Open your images and scale them to your required size, Copy one of the file then “paste” it as a layer in the other file.
Create a third empty layer and name it: “pattern mask”.
On this one, we will create a mask, which will alternatively cut and save half a lens of information from one image and block information from the other image.
If the optical pitch is 75,54 LPI; you must scale your file to the final size (including bleed) to 151,08 dpi (75,54 LPI x 2 images).

2)    Create the “Mask”:
a)    Create a new file from the menu and give any name (don’t open it yet).
b)    Set the “Width” and “Height” to 2 pixels (corresponding to the number of images you are interlacing)
c)    Set the resolution to 151,08 PPI, it must correspond to your final interlaced file: pitch (75,54) x number of images (2).
d)    Use the color mode you are using for your images.
e)    Select “white” content.
f)    Then “OK” to finalize the file.

3)    Creating the “Pattern” in this new file:
a)    Zoom to the maximum and use the selection tool (“Marquee tool”), select one pixel line or column (horizontal is better for flip and vertical is mandatory for 3D)
b)    Feel this selection in black: in the menu bare go to: “Edit”-->”Fill” and select “Black” for the “Content” dropdown menu.
c)    Our “Pattern” is ready:  “Select All”, in the menu; choose “Edit”--> “Define Pattern” and save this with a name like “Flip 2 horizontal”.

4)    Back to interlacing:
a)    In your image file (in layers)go to the layer named “pattern mask”, in the menu : ”Select” -->”All”,  then in menu again: “Edit” --> ”Fill” for “Content” choose “Pattern” and choose the “Pattern you just made. This will feel the layer with the selected “Pattern”.
b)    Turn this grid into a selection:  in the menu “Selection” --> “Color Range”  select “Shadows”, this will select the black lines.
c)    Save the selection: menu “Selection” --> “Save Selection”. Give it a name i.e.: “Mask”
d)    Go to your first “Layer”; in the menu “Layer” --> “Layer Mask” --> “Reveal Selection”. This will reveal the image information sitting behind the selection (half a lens).
e)    Go back to your layer “pattern mask” and move it from one pixel and repeat and the step: d) on the second image layer, and this will fill the other half lens with image 2.
f)    Flatten your result and it is ready to output.

You will use the same procedure for any amount of frames to interlace, the only difference is you will be repeating step 4) d) and e) the number of time equal your number of layers used.

Don't hesitate to contact us if you have any question about the above procedure.