Image pickup apparatus with function of rate conversion processing and control method therefor

• US 7,860,321 B2
• Filed: 09/21/2005
• Issued: 12/28/2010
• Est. Priority Date: 09/21/2004
• Status: Expired due to Fees

• Current Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Original Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Inventors: Watanabe, Yoshinori, Rengakuji, Hideyuki
• Primary Examiner(s): Mehta; Bhavesh M
• Assistant Examiner(s): MACKOWEY, ANTHONY M
• Application Number:
  US11/231,838
• Publication Number:
  US 20060114334A1
• Time in Patent Office: 1,924 Days
• Field of Search: 382/232, 382/236, 386/5, 386/6, 348/441, 348/443, 348/446, 348/454, 348/459
• US Class Current: 382/232
• CPC Class Codes: H04N 23/633 for displaying additional information relating to control or operation of the camera
• CPC Class Codes: H04N 5/772 the recording apparatus and the television camera being placed in the same enclosure

Abstract

A rate conversion unit determines a frame thinning-out rate to thin out frames on the basis of a recording rate at the time of photographing and a display rate for display on a display apparatus so that a temporal updating interval of a video image between continuous fields becomes constant. After that, a frame is repeatedly inserted so that a frame rate becomes equal to the display rate.

Claims

1. An image pickup apparatus, comprising:

an image pickup unit for picking up an object image;

a recording unit for recording image data obtained by the image pickup unit onto a recording medium;

a display unit selectively displaying an image related to any one of the image data obtained by the image pickup unit and the image data recorded on the recording medium on a display apparatus;

an image thinning-out unit for comparing a rate at the time of photographing of the image to be displayed by the display unit and a display rate in the display apparatus and if the rate at the time of photographing is higher than the display rate, thinning out the image to be displayed by the display unit, at a predetermined interval to lower the rate, thereby generating a display image of a rate lower than the display rate; and

a rate conversion unit for inserting repeatedly output images to the display image generated by the image thinning-out unit to increase the rate of the display image so that the rate of the display image is made equal to the display rate.

2. An apparatus according to claim 1,

wherein the image thinning-out unit includes:

a comparison unit for comparing the rate at the time of photographing and the display rate with each other;

a dividing value calculation unit for calculating a dividing value k corresponding to thinning out k−

1 frames after displaying one image frame, on the basis of the result of comparison by the comparison unit; and

a thinning-out processing unit for performing thinning-out processing of the image in accordance with the dividing value k,

wherein the image thinning-out unit thins out the frame in accordance with the dividing value k.

3. An apparatus according to claim 2, wherein the dividing value calculation unit includes:

a first initialization unit for initializing the dividing value k to 1 to provide the initialized dividing value k to the image thinning-out unit if the rate at the time of photographing is equal to or lower than the display rate as a result of comparison by the comparison unit;

a second initialization unit for initializing the dividing value k to 2 to provide the initialized dividing value k if the rate at the time of photographing is higher than the display rate as a result of comparison by the comparison unit; and

a dividing value increment unit for incrementing the dividing value k initialized by the second initialization unit one by one until a frame rate obtained by dividing the rate at the time of photographing by k becomes equal to or lower than the display rate, to provide the dividing value k corresponding to the frame rate equal to or lower than the display rate to the frame thinning-out unit.

4. An apparatus according to claim 1, wherein the recording unit includes:

a compression unit for compression-encoding the image data obtained by the image pickup unit to generate compressed image data;

a rate information addition unit for adding information related to the rate at the time of the photographing to the compressed image data; and

a compressed image data recording unit for recording the compressed image data onto the recording unit.

5. An apparatus according to claim 4, further comprising:

an expansion unit for reading out and expanding the compressed image data recorded on the recording medium; and

a rate information reading unit for reading out the information related to the rate at the time of the photographing, which information is added to the compressed image data.

6. An apparatus according to claim 5, wherein the image thinning-out unit determines an image thinning-out rate by comparing the information related to the rate at the time of the photographing which information is added to the compressed image data, and the display rate in the display apparatus, when a reproduced image on the recorded medium is displayed on the display apparatus by the display unit.

7. An apparatus according to claim 1, further comprising operation unit for setting a recording rate at the time of a photographing operation,

wherein the image thinning-out unit determines the image thinning-out rate by comparing the recording rate set by the operation unit and the display rate in the display apparatus, when the object image picked up by the pickup unit is displayed by the display unit on the display apparatus in parallel to the image pickup of the object image by the image pickup unit.

8. An apparatus according to claim 1, wherein the image thinning-out unit determines the image thinning-out rate by comparing a value obtained by multiplying a magnification of the reproduction speed of reproduction of the image data from the recording medium by the rate at the time of the photographing, and the display rate.

9. An apparatus according to claim 8,

wherein the image thinning-out unit includes:

a multiplication unit for multiplying the magnification of the reproduction speed with respect to an image pickup speed by the rate at the time of the photographing to obtain a multiplied frame rate;

a comparison unit for comparing the multiplied frame rate and the display rate with each other;

a dividing value calculation unit for calculating a dividing value k corresponding to thinning out k−

1 frames after displaying one image frame, on the basis of the result of comparison by the comparison unit; and

a thinning-out processing unit for performing thinning-out processing of the image frame in accordance with the dividing value k.

10. An apparatus according to claim 9, wherein the dividing value calculation unit includes:

a first initialization unit for initializing the dividing value k to 1 to provide the initialized dividing value k to the image thinning-out unit if the multiplied frame rate is equal to or lower than the display rate as a result of comparison by the comparison unit;

a second initialization unit for initializing the dividing value k to 2 to provide the initialized dividing value k if the multiplied frame is higher than the display rate as a result of comparison by the comparison unit; and

a dividing value increment unit for incrementing the dividing value k initialized by the second initialization unit one by one until a frame rate obtained by dividing the multiplied frame rate by k becomes equal to or lower than the display rate, to provide the dividing value k corresponding to the frame rate equal to or lower than the display rate to the image thinning-out unit.

11. A method of controlling an image pickup apparatus including an image pickup unit for picking up an object image, a recording unit for recording image data obtained by the image pickup unit onto a recording medium, and a display unit for selectively displaying the image from the image pickup unit and the recording image recorded onto the recording medium on a display apparatus, the method comprising:

an image thinning-out step of comparing a rate at the time of photographing of the image to be displayed by the display unit and a display rate in the display apparatus and if the rate at the time of photographing is higher than the display rate, thinning out the image to be displayed by the display unit, at a predetermined interval to lower the rate, thereby generating a display image of a rate lower than the display rate;

a rate conversion step of inserting repeatedly output images to the image generated in the image thinning-out step to increase the rate of the display image so that the rate of the display image is made equal to the display rate; and

a display step of displaying the image whose rate is converted in the rate conversion step on the display apparatus.

12. A computer-readable recording medium storing a program comprising program code for causing a computer to execute a control procedure of an image pickup apparatus including an image pickup unit for picking up an object image, a recording unit for recording image data obtained by the image pickup unit onto a recording medium, and a display unit for selectively displaying the image from the image pickup unit and the recording image recorded onto the recording medium on a display apparatus, the program comprising:

code for an image thinning-out procedure of comparing a rate at the time of photographing of the image to be displayed by the display unit and a display rate in the display apparatus and if the rate at the time of photographing is higher than the display rate, thinning out the image to be displayed by the display unit, at a predetermined interval to lower the rate, thereby generating a display image of a rate lower than the display rate;

code for a rate conversion procedure of inserting repeatedly output images to the display image generated in the image thinning-out procedure to increase the rate of the display image so that the rate of the display image is made equal to the display rate; and

code for a display procedure of displaying the image whose rate is converted in the rate conversion procedure on the display apparatus.