FR3079708A1 - METHOD FOR PROJECTING AN IMAGE ON AN ENHANCED CONTRAST SCREEN - Google Patents

Abstract

A method of projecting an image (1) onto a screen (2), in which an image (1) is projected on a screen (2) by means of projection means (3) positioned at a distance from the screen screen (2), said image (1) being delimited on the screen (2) by a contour (4). According to the invention, a light frame (5) of uniform color is projected onto the screen (2), simultaneously with the image (1), matching the outline (4) delimiting said image (1), said light frame (5) being configured to enhance the perceived contrast of said image.

Description

The present invention relates to a method of projecting an image onto a screen making it possible to improve the contrast of the image.

The invention also relates to an installation configured to implement the method according to the invention.

The field of the invention is that of methods of projecting an image on a screen, implemented for example for the projection of static or dynamic images, in particular for the broadcasting of videos.

As is well known, in such a method, an image is projected onto a screen by projection means positioned at a distance from the screen, the projection means comprising for example a video projector, possibly connected to a video source, for example a computer or BLU RAY ® reader. When projected on the screen, said image is delimited by an outline on the screen.

In a well known manner also, black corresponds to the total absence of light, and it is therefore particularly complicated to restore black on an image projected by a light source.

Thus, the contrast of a projected image is defined by the ratio between the light intensity of the lightest shades projected by the projection means and the light intensity of the darkest shades. Generally, the contrast obtained for a projected image is between 800: 1 and 4000: 1, depending on the characteristics of the projection means used.

Therefore, depending on the contrast of the projected image, and in particular when it is low, there must be sufficient darkness in the room in which the image is projected so that the image is perceived by an observer with good rendering of the images. black, ie a clear distinction between dark and light shades in the image.

According to the inventor's observations, the perception of deep blacks on a projected image is never optimal, even in the dark: the diffuse light implicit in the projection process pollutes the darkest surfaces of the image and prevents a correct perception of the dark surfaces of the image (blacks), even of certain colors.

The invention therefore proposes to overcome these drawbacks by providing a method of projecting an image on a screen making it possible to restore an image with a high perceived contrast, simple to implement and at low cost.

More particularly, the invention will allow a better perception of the dark surfaces of the projected image.

Other advantages of the invention will appear during the description which follows and is given only for information.

Also, the invention relates to a method of projecting an image onto a screen, in which an image is projected onto a screen by means of a projection means positioned at a distance from the screen, said image being delimited on the screen by an outline.

According to the invention, a uniform colored light frame is projected onto the screen, simultaneously with the image, conforming to the outline delimiting said image, said light frame being configured to improve the perceived contrast of said image.

According to optional features of the invention, taken alone or in combination:

- we project the light frame with a brightness greater than or equal to the brightness of the image,

- the light frame is a closed curve of constant thickness, the light frame being projected with a thickness of between 3 and 10 pixels of the projected image,

- the said light frame is projected by the same means of projection as that projecting the image,

the projection means comprises a video projector,

- said projection means projecting the image is said first projection means, and in which said light frame is projected by means of a second projection means, distinct from the first projection means,

the second projection means comprises a video projector,

the second projection means comprises a laser,

- we project the red light frame,

- we project the yellow light frame,

- we project a dynamic image and we project a static light frame.

The invention will be better understood on reading the following description accompanied by the appended figures, among which:

FIG. 1 is a front view of an image projected during the projection process according to an embodiment according to the invention,

FIG. 2A is a perspective view of an installation making it possible to implement the projection method according to a first embodiment in accordance with the invention,

FIG. 2B is a schematic representation of a part of the installation in accordance with the installation of FIG. 2A, according to a first alternative,

FIG. 2C is a schematic representation of a part of the installation in accordance with the installation of FIG. 2A, according to a second alternative,

FIG. 3A is a perspective view of an installation making it possible to implement the projection method according to a second embodiment in accordance with the invention,

FIG. 3B is a schematic representation of a part of the installation in accordance with the installation of FIG. 3A, according to a first alternative,

FIG. 3C is a schematic representation of part of the installation in accordance with the installation of FIG. 3A, according to a second alternative,

- Figure 3D is a schematic representation of the laser that can be used in the installation of Figure 3A.

The invention relates to a method of projecting an image 1 onto a screen 2, in which an image 1 is projected onto a screen 2 by means of a projection means 3 positioned at a distance from the screen 2, said image 1 being delimited on the screen 3 by an outline 4,

The projection process is implemented in total or partial darkness, in a manner well known from the state of the art. According to this state of the art, and as mentioned in the introduction, the perception of deep blacks on a projected image is never optimal, which alters the perceived contrast.

Even in the dark and according to the inventor's observations, the diffuse light implicit in the projection process pollutes the darkest surfaces of the projected image and prevents a correct perception of the dark surfaces of the image (black) , or even certain colors.

The invention makes it possible to significantly improve the perception of dark surfaces by reference to this prior art, and thus the perceived contrast of the image.

According to the invention, a light frame 5 of uniform color coming onto the outline 4 delimiting said image 1 is projected onto the screen 2, simultaneously with image 1, said light frame 5 being configured to improve the perceived contrast of said image. picture 1.

Thus, an observer who will look at said image will perceive in his field of vision, simultaneously with image 1 said light frame 5.

The light frame 5 retracts the retinas of the user (by reference to a projection process without a light frame, as known from the prior art): the perception of the dark surfaces of the image 1 projected on the interior of the frame is then significantly improved, and thus the contrast: the blacks appear deep.

Therefore, even if the observer is in a room with reduced darkness, and the contrast of the projected image 1 is low, for example of the order of 800: 1, the blacks and colors will appear more distinctly, thanks to this reinforced impression of darkness created for the observer.

Advantageously, said image 1 can be a static image, such as for example a photograph or an illustration. Alternatively, said image 1 can be a dynamic image, such as for example a video.

According to the embodiment shown in Figures 1 to 3, the outline 4 of the image 1 and therefore the light frame 5 can be rectangular. Alternatively, the outline 4 of image 1 and therefore the light frame 5 can be of any other shape.

Screen 2 is any surface on which the image is projected, whether it is a device specifically provided for this purpose, such as a canvas or PVC screen, or any surface on which the image is projected, such as for example a flat surface, such as a wall.

In a well known manner, and also in order to guarantee a satisfactory perceived contrast of the image, the screen 2 can be a flat and smooth surface, of uniform clear color, in particular white.

According to one embodiment, the light frame 5 is projected with a brightness greater than or equal to the brightness of the image 1.

The brightness considered here is that emitted by the projection means 3 used to project said image 1, and in particular by the light source of said projection means 3.

Such luminosity is generally expressed in lumens and generally has a value which can vary between a few hundred lumens and several thousand lumens.

As explained above, and according to the inventor's findings, the improvement in the perceived darkness for an observer of the projected image 1 will be significant and will allow a better perceived contrast of the image when the brightness of the light frame 5 will be identical to that of the projected image 1. However, this effect will be accentuated if the brightness of the light frame 5 is higher than that of the projected image 1.

According to one embodiment, the light frame 5 is a closed curve of constant thickness e, the light frame 5 being projected with a thickness e of between 3 and 10 pixels of the projected image 1.

In the same way as previously, according to the inventor's observations, the greater the thickness e of the light frame 5 relative to the size of the projected image 1, the more the darkness perceived by the observer and therefore the perceived contrast of image 1 will be better.

As is well known, a pixel is the unit used to specify display definitions. For example, a high definition image corresponds to a rectangular image of 720 base pixels and 576 pixels high, or 414,720 pixels.

The size of a pixel therefore depends on the size of the image in the context of a projected image 1.

According to one embodiment, said light frame 5 is projected by means of the same projection means 3 as that projecting the image 1.

This advantageous arrangement of the invention makes it possible to simplify the production of an installation implementing said method according to the invention and to reduce its cost price, as can be seen in the exemplary embodiment of FIG. 2a.

According to a first alternative, shown for example in the embodiment of FIG. 2b, the frame 5 and the image 1 can be generated by the same source SI, for example by means of one or more software programs executed by same computer means, such as for example a personal computer (PC), the image 1 provided with the frame 5 then being transmitted by the source SI by means of projection 3.

According to a second alternative, represented for example in the embodiment of FIG. 2c, the image 1 can be generated by a first source SI, for example by means of software executed by a first computer means, by example a PC, then transmitted to a second source S2, for example a second computer means, such as a “scaler” (scaler in French language), the image 1 provided with the frame 5 then being transmitted by the second source S2 to the projection means 3.

According to one embodiment, the projection means 3 comprises a video projector.

Such an embodiment can be seen, for example, in the example of embodiment in FIG. 2a.

According to one embodiment, said projection means 3 projecting the image 1 is said to be first projection means 3, and said light frame 5 is projected by means of a second projection means 3 ′, distinct from the first means of projection 3.

Such an embodiment is visible for example in the embodiment of Figure 3a.

This advantageous arrangement of the invention makes it possible in particular to project the light frame 5 with a brightness greater than that of the projected image 1, this arrangement cannot in fact be implemented with an installation in which the light frame 5 and the image 1 are projected with the same projection means 3.

According to a first alternative, represented for example in the embodiment of FIG. 3b, the image 1 can be generated by a first source SI, for example by means of software executed by a first computer means, by example a PC, then transmitted to the first projection means 3, while the frame 5 can be generated by a second source S2, for example by means of software executed by a second computer means, for example a PC, then transmitted to the second projection means 3 '.

According to a second alternative, represented for example in the embodiment of FIG. 3c, the image 1 can be generated by a source SI, for example by means of software executed by computer means, for example a PC, then transmitted to the first projection means 3, while the frame 5 can also be generated by said source SI, for example by means of software executed by said computer means, for example a PC, then transmitted to the second projection means 3 '.

According to one embodiment, the second projection means 3 ’comprises a video projector.

Such an embodiment is visible for example in the example of embodiment in FIG. 2a.

According to one embodiment, the second projection means 3 ′ comprises a laser.

Said laser can advantageously be incorporated into a laser projection device, making it possible to project a laser beam 31 ’in a desired shape. As can be seen in the embodiment of FIG. 3D, such a laser projection device can include different elements making it possible to project a laser beam 31 ′ according to the shape and with the desired intensity on the screen 2. Thus, after having been emitted by a laser source 32 ', said laser beam 31' passes through an adaptation device 33 ', comprising for example a divergent lens followed by a collimator. The laser beam 31 ′ can then be amplified by means of an amplification device 34 ′, comprising for example a doped fiber amplifier, before being shaped by a shaping means 35 ′ to be projected at the desired shape on the screen 2, in particular with a rectangular shape.

According to one embodiment, the light frame 5 of red color is projected.

By red color is meant that the frame is generated with a uniform color whose wavelength is between 620 and 700 nm.

According to the inventor's observations, the use of the color red for the light frame 5 is particularly advantageous in that it is with this color that an observer will have the best impression of darkness created by the light frame 5.

According to one embodiment, the light frame 5 of yellow color is projected.

By yellow color is meant that the frame is generated with a uniform color whose wavelength is between 577 and 600 nm.

According to the inventor's observations, the use of the color yellow for the light frame 5 also gives satisfactory results in terms of the impression of darkness created by the light frame 5.

According to one embodiment, a dynamic image 1 is projected and a static light frame 5 is projected.

By static light frame 5 is meant that the light frame 5 does not change color or thickness e and is projected with constant brightness during the diffusion of image 1, and while image 1 evolves , meanwhile, over time.

The shape and the dimensions of the frame 5, apart from its thickness e, can vary during the diffusion of the image 1, in particular to adapt to the possible variations of the shape and the dimensions of the outline of the image 1 during of its dissemination.

Thanks to this advantageous arrangement of the invention, the light frame 5 will be well perceived by an observer in order to improve the impression of darkness, but will not focus the attention of the observer, unlike dynamic image 1 projected.

According to the inventor's observations, after a slight adaptation time for the observer of the projected image 1 to the presence of the light frame 5, it thus fulfills its function of improving the impression of darkness without disturb the observation of image 1 by the observer.

Naturally, other embodiments could have been envisaged by the skilled person without departing from the scope of the invention defined by the claims below.

NOMENCLATURE

The image

2. Screen

3. Means of projection / video projector

3 '. Projection medium / video projector / laser

31. Laser ray

32 '. Laser source

33’. Adapter

34 '. Amplification device

35 '. Means of shaping

4. Contour

5. Light frame

SL First source

S2. Second source

Claims (11)

1. Method for projecting an image (1) onto a screen (2), in which an image (1) is projected onto a screen (2) by means of a projection means (3) positioned remotely of the screen (2), said image (1) being delimited on the screen (2) by an outline (4), characterized in that one projects onto the screen (2), simultaneously with the image (1), a light frame (5) of uniform color coming to match the outline (4) delimiting said image (1), said light frame (5) being configured to improve the perceived contrast of said image. 2. The projection method according to claim 1, in which the light frame is projected with a brightness greater than or equal to the brightness of the image. 3. A projection method according to claim 1 or 2, wherein the light frame (5) is a closed curve of constant thickness (e), the light frame (5) being projected with a thickness (e) between 3 and 10 pixels from the projected image (1). 4. A projection method according to one of claims 1 to 3, wherein said light frame (5) is projected via the same projection means (3) as that projecting the image (1). 5. A projection method according to one of claims 1 to 4, wherein the projection means (3) comprises a video projector. 6. A projection method according to one of claims 1 to 3, in which said projection means (3) projecting the image (1) is said to be first projection means (3), and in which said light frame is projected ( 5) by means of a second projection means (3 '), distinct from the first projection means (3). 7. The projection method according to claim 6, wherein the second projection means (3 ’) comprises a video projector. 8. The projection method according to claim 6 or 7, wherein the second projection means (3 ’) comprises a laser. 9. A projection method according to one of claims 1 to 8, in which the light frame (5) of red color is projected, generated with a uniform color whose wavelength is between 620 and 700 nm. 10. A projection method according to one of claims 1 to 9, in which the light frame 5 (5) of yellow color generated with a uniform color whose wavelength is between 577 and 600 nm is projected. 11. A projection method according to one of claims 1 to 10, in which a dynamic image (1) is projected and a static light frame (5) is projected.