GB2384381A

GB2384381A - Camera incorporating tilt sensor

Info

Publication number: GB2384381A
Application number: GB0200989A
Authority: GB
Inventors: James Leigh Taylor
Original assignee: Individual
Current assignee: Individual
Priority date: 2002-01-17
Filing date: 2002-01-17
Publication date: 2003-07-23
Also published as: GB0200989D0

Abstract

A camera incorporates a tilt sensor whose output is acquired by image acquisition means. The additional orientation data so acquired may be used to determine the vertical orientation of any image acquired, hence the image may be processed or presented in the correct orientation. Preferably the tilt sensor differentiates the four main orientations of the camera and hence the image (level, left portrait, right portrait, inverted). Preferably the tilt sensor also detects a high angle of inclination or declination of the camera in which case the image should be interpreted as if the camera were level. The tilt sensor (Fig. 7) may comprise a ball bearing within chamber with 4 facets (23-26) for determining tilt and 2 facets (27, 28 for determining inclination). The ball bearing may be replaced by mercury.

Description

CAMERA INCORPORATING TILT SENSOR The invention relates to a camera incorporating a tilt sensor so that orientation data may be acquired automatically at the time a photograph is taken.

In this description, the axis of the camera denotes the direction of the axis of the lens (if any), and is perpendicular (normal) to the plane of the image. The axis is the direction in which the camera "is pointing".

The orientation of the cwnera is the degree of rotation of the camera about its axis. For any camera there is a natural level orientation. The camera is normally held in level orientation when photographing a"landscape"scene (the width of the subject scene being wider than its height). However the camera may be rotated on its axis 90 degrees clockwise or anticlockwise (ghtportralt or leftportra), or rotated 180 degrees (mverted). These are the four main orientations of the camera.

The inclination of the camera is the angle of the axis above horizontal. The declination of the camera is the angle of the axis below horizontal. It is to be noted that when the axis is vertical, the orientation becomes undefined. As the axis approaches vertically up or down, the orientation becomes less important.

In the field of photography, most cameras take pictures which are rectangular not square. In composing a picture, such a camera may be oriented to take"landscape"or"portrait" pictures. For a"landscape"picture, the camera is held level, and the width of the picture taken is greater than its height. Conversely for a"portrait"picture the camera is rotated one quarter turn about the axis of the lens, and the width of the resultant image is less that its height.

For a conventional film camera (using for example 35 mm slide or print film, and a chemical development process), the resultant image is often rendered either as a slide or a print-a physical object that can easily be manipulated by hand. The orientation of the image is inferred from the scene by the person examining the photograph, who can then turn the photograph the"right way up". Such a process is so natural that it passes almost without thought.

Alternatively a digital image may be captured. This may result from capture by a digital camera, or from digital post-processing of an image from a film camera (for example images from films may be processed onto CD-ROM). Under software control, such images may then be displayed onto a computer screen.

Ordinarily there is insufficient data associated with each image to differentiate landscape and portrait pictures automatically so that each may be displayed in the correct orientation on the computer screen. At some point in the process manual input is required to differentiate portrait and landscape so that an appropriate rotation may be made to display the image the right way up. Furthermore there are two orientations in which a portrait picture may be taken (left and right portrait). It is unusual to take a picture with the camera inverted.

Manual input is required because it is very difficult for the computer to infer the correct orientation from the image itself-something which humans can usually do with ease, so the computer needs additional data relating to the orientation of the image.

Manual input of the orientation information is tedious, time consuming and boring. It would be better if orientation data were collected automatically.

An object of this invention is to provide for the automatic collection of image orientation data at the time the photograph is taken. This additional data is used by software to process or display the image automatically in the correct orientation.

The invention may be applied to still picture or moving picture photography. The image and associated data may be stored within the camera, or immediately transmitted to other equipment outside the camera.

This invention provides a camera incorporating or combined with a tilt sensor so that orientation data is acquired automatically at the time a photograph is taken.

The orientation data so collected is recorded or transmitted along with the image data and any other data relevant to that image (for example time stamp). Software uses the orientation data so gathered to infer the correct orientation of the image for processing or display.

Preferably the tilt sensor is mounted to detect the component of gravity within the plane of the image (normal to the axis of the camera).

Preferably the tilt sensor is able to differentiate between the four main orientations of the camera-level, left portrait, right portrait and inverted.

Preferably the tilt sensor is able to detect when the inclination or declination of the camera is high (the axis is near vertical up or down). In such cases the orientation information should be disregarded, and the image should be displayed as if the camera had level orientation.

Three preferred embodiments of the invention will now be described with reference to the accompanying drawings in which: FIGURE 1 shows a functional diagram of the camera incorporating a tilt sensor.

FIGURE 2 shows a view of the image data and tilt sensor data in combination according to a first embodiment.

FIGURE 3 shows example data captured with the camera held in level orientation FIGURE 4 shows example data captured with the camera held in right portrait orientation FIGURE 5 shows example data captured with the camera held in left portrait orientation FIGURE 6 shows example data captured with the camera held in inverted orientation FIGURE 7 shows a design for a tilt sensor suitable for this invention according to a third embodiment Figure 1 shows a functional diagram of the camera. The camera 1 incorporates a tilt sensor 2 together with the usual image acquisition/processing/storage/transmission means 3.

Orientation data from the tilt sensor 2 flows to the image acquisition/processing/storage/transmission means 3 as depicted by the arrow 4. The orientation data is acquired/processed/stored/transmitted along with the image data.

FIRST EMBODIMENT In a first embodiment as shown in Figure 2, the tilt sensor comprises two tilt switches whose outputs are denoted by arrows 10 and 11 respectively. In later figures, the output from each switch will be denoted by the direction of the arrows 10 and 11 (the arrow will point generally downwards), but in figure 2 arrows 10 and 11 are double-headed to indicate the range of possible outputs Tilt switch 10 detects whether the camera is rotated anticlockwise more than a reference amount (for example 45 degrees from level). Similarly tilt switch 11 detects whether the camera is rotated clockwise more than a reference amount.

The image captured by the image acquisition means is denoted by the contents of box 12.

Figure 3 shows the data acquired from a mountain scene with the camera in level orientation.

It will be seen that the two arrows 10 and 11 indicate the bottom edge of the scene. Hence it can be deduced that the image requires no corrective rotation prior to being displayed.

Figure 4 shows the data acquired from a portrait picture taken with the camera in right-portrait orientation (rotated 90 degrees clockwise). Again the two arrows 10 and 11 indicate the bottom edge of the scene. Hence it can be deduced that the image requires a 90 degree clockwise rotation prior to being displayed.

Figure 5 shows the data acquired from a portrait picture taken with the camera in left-portrait orientation (rotated 90 degrees anticlockwise). Again the two arrows 10 and 11 indicate the bottom edge of the scene. Hence it can be deduced that the image requires a 90 degree anticlockwise rotation prior to being displayed.

Figure 6 shows the data acquired from a portrait picture taken with the camera in inverted orientation (this is somewhat unusual). Again the two arrows 10 and 11 indicate the bottom edge of the scene. Hence it can be deduced that the image requires a 180 degree rotation prior to being displayed.

So for all 4 main orientations of the camera, there is sufficient orientation information for processing software to infer the correct orientation and hence display the image correctly.

SECOND EMBODIMENT In a second embodiment, the tilt sensor is implemented by a single tilt switch that detects whether the camera is in or close to level orientation (within a reference angle of level).

Hence the orientation data acquired is binary (level or not level orientation).

This second embodiment is cheaper than the first because it only requires a single binary tilt switch.

If the tilt sensor indicates level orientation, then the image can be displayed as-is. However there is a problem in the other case, when the tilt sensor indicates not level orientation.

In this latter case, a best guess has to be made as to the actual orientation of the camera. The camera is unlikely to have inverted orientation, but there are two other possible orientationsleft portrait and right portrait.

Assuming that the photographer is creature of habit, one or other portrait orientation may dominate. However which one is dominant may vary from person to person, dependant for example on whether the photographer is left handed or right handed.

Therefore, in this embodiment, at some point a preferred portrait orientation needs to be chosen. This can be set once as a personal preference setting for either the camera or the processing software. Once set, the selected portrait orientation will be used automatically for those photographs for which the tilt sensor indicates not level orientation.

THIRD EMBODIMENT In a third embodiment, the tilt sensor comprises a tilt switch according to Figure 7. This comprises a fully enclosed convex chamber 21 within which a ball bearing 29 runs. A"plan" and a"side"view of the chamber 21 are shown. A second side view is not shown because the chamber has rotational symmetry order 4 about the back-front axis, so the second side view would be substantially the same as the first.

For clarity the ball bearing 29 is shown separated from the chamber 21, but in reality runs within the chamber 21. Preferably the walls of the chamber 21 are made of plastic, and the ball bearing 29 is made of steel.

The chamber 21 (containing ball bearing 19) is mounted within the camera with the main axes of the chamber matching those of the camera. The back-front axis lies parallel with the axis of the camera. The top-bottom and left-right axes lie within a plane parallel to the image plane, with the obvious orientation with respect to the camera.

The chamber 21 has six key facets. They are bottom 23, top 26, left 24, right 25, back 27 and front 28. Because the chamber 21 is convex, the ball bearing 19 is free to fall to the lowest point in the chamber, which will normally be one of the key facets.

The location of the ball on each of the six key facets indicates the orientation/inclination/declination of the camera and corrective processing as follows

Facet Orientation/IncMaation/DecMnation Corrective processing Bottom 23 Level Display as is Left 24 Left Portrait Rotate 90 degrees anticlockwise Right 25 Right Portrait Rotate 90 degrees clockwise Top 26 Inverted Rotate 180 degrees Back 27 High inclination Display as is Front 28 High declination Display as is It is not necessary to distinguish the level, high inclination and high declination cases from each other because the processing is the same for each of these three cases.

Therefore it suffices to identify the left portrait, right portrait and inverted cases. Sensing of the inverted case is optional because it is rare.

The position of the ball bearing is sensed with appropriate sensors located at the left facet 24, the right facet 25 and optionally the top facet 26.

The ball bearing may be sensed using variable reluctance sensors (which sense an increase in inductance in an electrical coil when the ball bearing is nearby), but other choices are also available. For example the chamber walls may be conducting, and a simple contact sensor used.

The ball bearing may also be replaced with a quantity of mercury.

The orientation data is then acquired/processed/stored/transmitted as described previously.

Although the invention arises originally from a problem in displaying pictures in the correct orientation on a computer screen, other applications may arise.

For example a film camera may incorporate a simple damped pendulum perhaps in the shape of an arrow, whose image is superimposed on a small portion of the image when a photograph is taken. This would allow the vertical direction to be determined absolutely in the absence of suitable visual cues within the scene itself.

The invention may also be realised by an add-on tilt sensor accessory that may be fitted to a camera suitably designed to receive it.

Claims

CLAIMS 1. A camera incorporating a tilt sensor so that the orientation of the camera may be determined when a picture is taken.
2. A camera as claimed in claim 1 where the tilt sensor comprises one or more tilt switches.
3. A camera as claimed in any preceding claim where the tilt sensor can detect a high angle of inclination or declination of the camera.
4. A camera as claimed in any preceding claim where the image data and orientation data are acquired, processed or stored within the camera or transmitted from the camera to other equipment.
5. A camera as claimed in any preceding claim where the camera is capable of taking either still or motion pictures or both.
6. A camera as claimed in any preceding claim where the camera is a digital camera.
7. A camera substantially as herein described and illustrated in the accompanying drawings.
8. A tilt sensor accessory and camera that together effect the combination of camera and tilt sensor for the purposes described herein or together realise a camera as claimed in any preceding claim.
9. Software that processes orientation data and image data from a camera as claimed in any preceding claim such that the correct orientation of the image can be determined and hence the image may be processed stored or displayed in the correct orientation.