WO2005022202A2

WO2005022202A2 - A new method of creating an interlaced image for lenticular displays

Info

Publication number: WO2005022202A2
Application number: PCT/IL2004/000778
Authority: WO
Inventors: Itzhak Bar Yona
Original assignee: Lubartech Ltd.
Priority date: 2003-08-28
Filing date: 2004-08-26
Publication date: 2005-03-10
Also published as: WO2005022202A3; IL157648A0

Abstract

The invention is a new method for creating an interlaced image from two or more basic images. The method comprises the steps of: preparing digital image files having the same dimensions for each of the basic images; electronically cutting each of the digital image files into strips having the same width; using a software-instructed computer to merge the information contained in the basic images into a combined digital image file by arranging the strips in a predetermined manner; compressing the height of the combined digital image file uniformly to obtain the interlaced image, which has essentially the same dimensions as each of the digital image files for each of the basic images; and printing the interlaced image upon an indicia carrier. The novelty of the present method is that the strips are oriented in the interlaced image at a slant with respect to the principal axes of the interlaced image. The invention is also directed towards providing decoders for viewing the individual basic images of which the interlaced images of the invention are comprised.

Description

A NEW METHOD OF CREATING AN INTERLACED IMAGE FOR

LENTICULAR DISPLAYS

Field of the Invention

The presented invention is related to the field of lenticular displays.

Specifically, the invention provides a new method of creating the interlaced

image.

Background of the Invention

Lenticular displays are well known in the art and are all based on the same

basic elements, an interlaced image comprising two or more basic images printed on an indicia carrier and a transparent lenticular panel or sheet

comprising an array of lenses (lenticules) on one surface. If certain required

relationships between the lines of printing on the indicia carrier and the

lenticular panel are established and maintained, then either relative

motion, in a specific manner, between the two elements (dynamic systems)

or changing the viewing angle of the interlaced image through the lenticular

panel (static systems) will result in a display in which the basic images that

have been encoded into the interlaced image are alternately revealed to the

viewer. The required relationships relate to, for example, the pitch of the printing and lenses of the array as well as the alignment and distance

between them.

In the prior art displays the printed interlaced image (and matching lens

sheet) generally has either a square or rectangular shape with the lines of print (and lenses) arranged to be parallel to either the horizontal or vertical

border of the image. To view the basic images that have been encoded into

the interlaced image, the relative motion or change in viewing angle is in

the direction perpendicular to the lines of print. To reveal adjacent basic

images, the distance of the motion must be equal to the width of a printed

line of the interlaced image (equal to the width of a single lens in the array

and containing information from each of the basic images) divided by the

number of basic images of which the interlaced image is comprised. If the

transition from one position to the other isn't accurately carried out, then

parts of the information from more than one basic image will be at the locus

of the focal points of the lenses in the array resulting in "ghosting", i.e. very

poor quality displays.

For small size lenticular displays, for example those in which the indicia

carrier is a page of a book or magazine, lenticular sheets with several tens of

lenses per inch (lpi) are commonly used. Thus to create a dynamic display

using a lenticular sheet 401pi showing "flips" between three basic images,

the lens sheet must be moved relative to the indicia carrier in steps of 0.2mm (one third of the lens width of approximately 0.6mm). In practice it is

difficult and relatively expensive to provide a mechanism capable of

providing such motion, especially if the mechanism is hand activated. The

problem becomes more difficult to overcome as the distance to be moved

becomes smaller, i.e. for higher resolution displays using a smaller pitch or

for displays providing more complex effects, such as motion, which require a

large number of basic images.

It is a purpose of the present invention to provide a lenticular display for

which the relative movement between the interlaced image and

corresponding lens sheet, to achieve a desired effect, is greater than that for

a prior art display having the same pitch.

Further purposes and advantages of this invention will appear as the

description proceeds.

Summary of the Invention

In a first aspect the present invention provides a method for creating an

interlaced image from two or more basic images. The method of the

invention comprises the following steps:

(a) preparing digital image files having the same dimensions for each of the basic images; (b) electronically cutting each of the digital image files into strips having the same width; (c) using a software-instructed computer to merge the information contained in the basic images into a combined digital image file by arranging the strips in a predetermined manner; (d) compressing the height of the combined digital image file uniformly to obtain the interlaced image. The digital file of the interlaced image has essentially the same dimensions as each of the digital image files for each of the basic images; and

(e) printing the interlaced image upon an indicia carrier.

The method of the invention is characterized in that the strips are oriented

in the interlaced image at a slant with respect to the principal axes of the

interlaced image.

In another embodiment of the invention, the digital image files and/or the

strips can be compressed before the strips are arranged in a predetermined

manner. The strips can be cut at a slant with respect to the principal axes of

the basic images before arranging them in a predetermined manner or the

compressed combined digital image file of a conventional interlaced image

can be electronically tilted and cropped to form the interlaced image of the invention. In another aspect, the invention is an interlaced image comprised of two or

more basic images, wherein the lines of print of the interlaced image are printed on the indicia carrier at a slant with respect to the principal axes of

the interlaced image.

In a further aspect, the invention provides decoders for viewing the

individual basic images of which an interlaced image is comprised. The

decoders of the invention comprise:

(a) a transparent lenticular panel having an array of lenses on one surface; and

(b) means for moving the lenticular panel relative to the lines of print of the interlaced image.

In the decoders of the invention, the lenses are arranged on the lenticular

panel at a slant relative to the direction of motion of the panel.

The means for moving the lenticular panel can comprise roller means

attached to the panel. Rotation of the roller means causes the panel to move

relative to the lines of print of the interlaced image.

The decoder of the invention can further comprise a rigid frame. Activation

of the means for moving the lenticular sheet causes the lenticular sheet to

move relative to the rigid frame. All the above and other characteristics and advantages of the invention will be further understood through the following illustrative and non-limitative

description of preferred embodiments thereof, with reference to the

appended drawings.

Brief Description of the Drawings

- Figs. 1A to 3B show the steps in creating an interlaced image according to the prior art;

- Figs. 4A to 4C schematically show the optical requirements for aa dynamic display for viewing each of the basic images of which an interlaced image is comprised ;

- Figs. 5A, 5B, and 5C are top, cross-sectional, and exploded views, respectively, showing schematically a preferred embodiment of a decoder;

- Fig. 5D shows a decoder for viewing the basic images in an interlaced image created according to the method of Figs. 1A to 3B;

- Figs. 6A to 7B show the steps in creating an interlaced image according to the present invention;

- Figs. 8A and 8B show decoders for revealing the basic images contained in an interlaced image created according to the method of the present invention; and

- Figs. 9A and 9B show the relationship between the distances moved by the lenticular panel of the decoder of Fig. 8 in the vertical direction and the motion of an individual lens in a direction orthogonal to the long axis of the lenses on the panel.

Detailed Description of Preferred Embodiments

The following definitions are used in this specification:

- The words "panel", "sheet", and "film" are used interchangeably to refer to a transparent substrate whose thickness is much less than its width or length and whose two principal planar faces are essentially parallel.

- The terms "lenticular panel", "lenticular sheet", and "lenticular film" are used interchangeably to refer to a panel, sheet, or film comprising an array of lenticules created on one of its principal faces.

- An "interlaced image" is a printed composite image made by dividing two or more different pictures into "strips", arranging the strips into a predetermined pattern and, optionally, performing other operations on the arrangement of strips before printing the arrangement on a suitable substrate.

- An indicia carrier is the substrate on which the interlaced image is printed. The indicia carrier can be composed of any suitable material such as paper or plastic sheet or film, it can be a single sheet or a page bound in a book or magazine. In the case of static displays, the indicia carrier can be the planar side of the lenticular panel opposite the array of lenses. - A "line" of print of the interlaced image is a line printed on the indicia carrier. Each line of print of the interlaced image contains one strip from each of the basic images and is the width of one of the lens on the array on the lenticular panel.

- The term "basic image" is used to refer to one of the two or more pictures that are sliced into strips to create the interlaced image.

- The term "masked image" refers to the set of strips in the interlaced image related to one of the basic images.

- A "decoder" is a device used to view the individual masked images concealed in the interlaced image, i.e. to reveal the basic image.

- A changing display refers to showing more than one image in the same location, for example to show a series of "still" images or to give the illusion of motion.

- A static display is a changing display based on lenticular technology wherein there is no relative motion between the indicia carrier and the lens sheet and the basic images are revealed by changing the viewing angle of the reader.

- A dynamic display is a changing display based on lenticular technology wherein the basic images are revealed by causing relative motion between the indicia carrier and the lens.

- One direction is considered to be at a "slant" with respect to a second direction if the two directions are neither parallel to each other nor mutually orthogonal. - The principal axes of a two dimensional image are the horizontal and vertical axes defined by the intrinsic orientation of the image when viewed by an observer.

As is well known to experienced persons, in practice an interlaced image is

created digitally using digital cameras and computers guided by appropriate

software and then stored in the computer's memory to be eventually printed

on a suitable substrate. The methods, hardware, and software required for

producing and printing interlaced images are well known in the art and will

not be discussed in detail hereinbelow for reasons of brevity.

In order to appreciate the basic requirements of creating a lenticular

display, one known method of creating an interlaced image comprised of

three separate basic images is demonstrated in Figs. 1A to 3.

In Figs. 1A to 1C are shown three basic images, in this case block letters A,

B, and C respectively. The images in Figs. 1A, IB, and 1C are recorded

graphically or with a digital camera and stored as digital image files in the memory of a computer.

In the next steps in creating the interlaced image, shown in Figs.2A to 2C,

the sizes of the basic images are adjusted resulting in three digital image

files, each having height H and width W. Each of the image files is then electronically cut into n equal horizontal strips. Each of the resulting n

strips for each of the image files has height h and width W, where h = H/n

is defined as the pitch of the interlaced image. In the present example, for

simplicity and clarity, n is chosen to be 19 and the strips are labeled

respectively A1-A19, B1-B19, and C1-C19. It should be noted that the

description herein for horizontal strips applies mutatis mutandis to

interlaced images formed by cutting the basic images into vertical strips.

Following instructions provided by the software, the computer then merges

the strips of the three basic images into a single combined digital image file

by arranging the fifty-seven strips of height h and width W in the order Al,

Bl, Cl A2, B2, C2, .... A19, B19, C19. The resulting combined image file,

shown in Fig. 3A, has height 3H and the same width W as each of the

original images.

Finally, the interlaced image, shown schematically in Fig. 3B, is obtained by

compressing the height of the combined image file uniformly to height H, in

order to retain the proper proportions in the images that will be observed

when looking at the interlaced image through the lenticular sheet. The

interlaced image is stored as a digital file in a computer and is eventually

printed on the indicia carrier using conventional means. The skilled observer will realize that the compression can also be carried out

on each of the individual strips of the basic images before arranging the

strips to form the composite image file, which in this case is the interlaced

image.

In order to be able to see the basic images that have been interlaced and

printed on the page, the interlaced image is viewed through an array of

lenticular lenses. The lenses can be of many types and shapes including

linear, spherical, cylindrical, Fresnel, etc. The type chosen of lens chosen is

the one that can be arranged with the same geometrical configuration as the

lines of printing suitable for the particular application. For example, an

array of linear cyhndrical lenses is used for viewing the interlaced images of

the type shown in Fig. 3B. If the requirements listed hereinbelow for a

lenticular display are met, then the basic images are alternately displayed

by changing the viewing angle of the interlaced image through the lenses or

by causing relative motion, in a controlled manner, between the interlaced

image and the lenses.

The fundamental requirements of a lenticular display are the following:

1. The pitch of the interlaced image must be essentially equal to the pitch of the lenses.

2. The distance between the interlaced image and the lenses must be constant and essentially equal to the focal length of the lenses. 3. Exact alignment between the interlaced image and the array of lenses must be established and maintained during the relative motion between the lenses and printing; e.g., in the case of the interlaced images shown in the Fig. 3B, the long axis of the printing on the indicia carrier must be essentially parallel to the long axis of the cylindrical lenses.

These requirements and methods of satisfying them are well known in the art and will not be further discussed herein for reasons of brevity.

Figs. 4A to 4C schematically show the optical requirements for viewing each

of the basic images using a dynamic display. Lenticular lens array 7 is created on the top face of transparent sheet 6 and the interlaced image 5 is

printed on the indicia carrier 8. The distance between the printing and the

top of the lenses (designated in the figures by the letter f) is constant and

essentially equal to the focal length of the cylindrical lenses that comprise the array. The interlaced image, in this case, is comprised of three basic

images A, B, and C. The pitches, h, of both the printed interlaced image and

of the lenses are equal. Arrows A, B', and C indicate how, at different

positions of the lenticular sheet relative to the lines of printing on the page,

looking through the lenses in a direction essentially perpendicular to the page will alternatively reveal basic images A, B, and C to the observer as

the relative motion occurs. The dashed lines in Figs. 4A to 4C show the

paths of the rays that pass through the edges of each of the lenses and are

focused on the printing and the unlabeled arrows the direction of the light rays reflected from the printing. The bold lettering An, An+i, etc. indicates

the image of line A_n, etc. of the interlaced image (refer to Fig. 3B) that is

viewed through the nth lens of the array.

Once the interlaced image has been printed directly on the indicia carrier,

an optical device, referred to as a "decoder", is provided to decode the

masked images, i.e. to allow the basic images comprising the interlaced

image to be individually observed. The principal component of the decoder is

a lenticular panel. In its basic form the decoder for a dynamic display

system comprises a transparent lenticular panel that is placed on the

indicia carrier over the interlaced image and aligned with the lines of print

and means for moving the lenticular sheet relative to the printed interlaced

image.

Figs. 5A, 5B, and 5C are top, cross-sectional, and exploded views,

respectively, showing schematically a preferred embodiment of a decoder

comprising means for slidably displacing the lenticular panel over the

interlaced image. The decoder 30 comprises lenticular panel 32 and

displacement means to slidably displace the panel. The displacement means

comprise roller means 36. The roller means are comprised of a rotatable axis

34 supported by two supports 40 at its extremities and provided with

contact points 38 on its surface to create a frictional force with the surface of the pages upon rotation. Alternatively, the roller means can be a solid roller

similar to that found in a typewriter.

The decoder is placed on the interlaced image and aligned with the lines of print. The roller means 36 are then rotated slightly (essentially rocked back and forth) and, as a result of the frictional force between the contact points

38 and the underlying indicia carrier, the panel is displaced relative to the

interlaced image and the basic images are sequentially revealed.

Fig. 5D is a top view, schematically showing another example of a decoder

10 that is capable of producing the above described effect. Part of the rigid

frame 12 has been removed in order to reveal internal details of the device. The decoder is placed over the interlaced image (not shown) and aligned

with the print and spaced such that the conditions listed hereinabove for producing a lenticular display are satisfied. The rigid frame 12 contains a

transparent lenticular panel 14 with a flat bottom side and an array of

vertical linear lenses on the outer surface. The panel 14 can be moved

vertically up and down by manual rotation of knob 16 around its axis 18.

Coaxial with knob 16, and permanently attached to it, is gear 20. The teeth

on gear 20 engage compatible teeth 22 created on the edge of panel 14. By means of this gear train the rotation of knob 16 is translated into linear

motion of the lenticular panel 14. The double headed arrows indicate the

direction of motion of the relevant part. In order to reduce friction and also to maintain the proper alignment of the lenses with respect to the printing,

two or more wheels 24 are attached to the frame 12 on the side of panel 14 opposite to the knob 16. Wheels 24 can be smooth as shown in the figure or can be gearwheels that engage teeth created on the edge of the panel in a

similar manner to the relationship between gear 20 and teeth 22. Thus, to

view the basic images, the viewer slowly rotes knob 16 with his finger causing the lenses to move up and down relative to the lines of print in the

interlaced image.

Other embodiments of the decoder can comprise means for attaching the

decoder to the print, means for establishment of and maintenance of alignment and spatial relationship between the print and the lenses, and

various other types of mechanism, manual and automatic, for causing the

relative motion. The embodiments described hereinabove are provided

merely as examples to illustrate the principles involved and are not intended to limit the scope of the present invention in any manner. Once the

basic principle of the invention is understood, the skilled person will have no

difficulty in suggesting alternative embodiments.

As discussed hereinabove, in the prior art method of creating the interlaced

image, there is a one to one relationship between the width of a line of print

of the interlaced image and the distance that the lenticular panel of the

decoder must be moved to change from viewing one basic image to the next one. The method of the present invention for creating the interlaced image shown in Figs. 6A to 6C, 7A, and 7B improves this situation by changing the relationship between the line width and distance the lenses must be moved.

In a preferred embodiment, the method of the invention for forming an interlaced image follows exactly the steps outlined above for the prior art

method and similarly is carried out using appropriately programmed

software and known printing techniques. The difference between the

invention and the prior art is in the manner in which the basic images are cut into lines. As shown in Figs.βA to 6C, in the present invention each of the basic images is electronically cut into a plurality of slanted strips,

instead of horizontal or vertical strips as in the prior art. Each of the strips

has a width s equal to the width of the lenses. The number of strips into

which each of the basic images is divided depends on the pitch of the lenses to be used, the size of the image, and the slant angle.

In another embodiment of the invention, the interlaced image can be formed

by cutting the basic images into either horizontal or vertical strips and the

combined digital image file is formed as in the prior art. Suitable computer

programming is then employed to electronically tilt the combined digital file

by a selected angle and to crop the resulting tilted digital file to form the interlaced image of the invention. Figs. 7A and 7B show respectively the combined image and the interlaced image formed according to the method of the invention.

Figs. 8A and 8B show decoders suitable for use with the interlaced images of

the invention. The decoders of Figs. 8A and 8B are identical to those shown

in Figs. 5A to 5D, with the exception that the lenses on the lenticular panel (32,14) are aligned at an angle with the horizontal that is equal to the slant

angle of the lines of printing of the interlaced image. Rotating roller means

36 or knob 16 will cause the lenses to move up and down vertically or back

and forth horizontally as described hereinabove but the motion will also

have a component that is perpendicular to the longitudinal axis of the lenses/ lines of print of the underlying interlaced image. In this case the

distance s' that the panel moves when changing from one basic image to the

next one, i.e. the perpendicular component of the motion, is not one third of

the lens width s as hereinabove, but the relationship between them depends on the slant angle with the horizontal.

Fig. 9 A shows the relationship between the distance s' moved by the

lenticular panel in the vertical direction and the distance s resulting from the component of motion of an individual lens in a direction orthogonal to

the long axis of the lenses/lines of print. If s is the width of an individual lens in the array, which is equal to the width of a line of print of the

interlaced image, then the lenticular panel 14 must move a distance s/3 to

move from one basic image to the next.

Fig. 9B is an enlargement of area A in Fig. 9A. From Fig. 9B it can be seen

that s = s' cosα. Thus, using the same example as hereinabove, i.e. a

lenticular sheet having 40 lpi and an interlaced image comprised of three

basic images; instead of 0.2mm, the panel must move ~0.3mm for α = 45°,

~0.4mm for α = 60°, and ~0.6mm for α = 70°.

Although embodiments of the invention have been described by way of

illustration, it will be understood that the invention may be carried out with

many variations, modifications, and adaptations, without departing from its

spirit or exceeding the scope of the claims.

Claims

1. A method for creating an interlaced image from two or more basic

images comprising the following steps: (a) preparing digital image files having the same dimensions for each of said basic images; (b) electronically cutting each of said digital image files into strips having the same width; (c) using a software-instructed computer to merge the information contained in said basic images into a combined digital image file by arranging said strips in a predetermined manner;

(d) compressing the height of said combined digital image file uniformly to obtain said interlaced image, which has essentially the same dimensions as each of said digital image files for each of said basic images; and (e) printing said interlaced image upon an indicia carrier;

wherein said strips are oriented in said interlaced image at a slant with

respect to the principal axes of said interlaced image.

2. A method according to claim 1, wherein the digital image files and/or

the strips are compressed before the information contained in the basic

images are combined by arranging said strips in a predetermined manner.

3. A method according to claim 1, wherein the strips are cut at a slant

with respect to the principal axes of the basic images.

4. A method according to claim 1, wherein the strips are cut either

horizontally or vertically with respect to the principal axes of the basic

images and the compressed combined digital image file is electronically tilted and cropped to form the interlaced image.

5. An interlaced image comprised of two or more basic images, wherein the lines of print of said interlaced image are printed on the indicia carrier

at a slant with respect to the principal axes of said interlaced image.

6. A decoder for viewing the individual basic images of which an

interlaced image is comprised, said decoder comprising:

(b) means for moving said lenticular panel relative to the lines of print of said interlaced image,

wherein said lenses are arranged on said panel at a slant relative to the

direction of motion of said panel.

7. A decoder according to claim 6, wherein the means for moving the

lenticular panel comprise roller means attached to said panel, wherein rotation of said roller means causes said panel to move relative to the lines of print of said interlaced image.

8. A decoder according to claim 6, further comprising a rigid frame and

wherein activation of the means for moving the lenticular sheet causes said lenticular sheet to move relative to said rigid frame.