Image transfer system, image transfer method, image reception apparatus, image transmission apparatus, and image pickup apparatus

1. An image transfer system, comprising:

an image transmission unit that transmits an image, the image transmission unit including a processor and a memory; and

an image reception unit that receives the image transmitted from the image transmission unit, the image reception unit including a processor and a memory, wherein:

the memory of the image transmission unit includes instructions which cause the processor of the image transmission unit to:

scale down the image, and

transmit the scaled-down image to the image reception unit; and

the memory of the image reception unit includes instructions which cause the processor of the image reception unit to:

calculate an angle between a line displayed in the image transmitted from the image transmission unit and a horizontal direction of the image in correspondence with pixels included in the image,

scale up the image transmitted from the image transmission unit, and

remove an aliasing component of the scaled-up image based on the calculated angle.

2. The image transfer system according to claim 1 , wherein:

the image is an image displayed by interlace scanning;

the processor of the image transmission unit is further caused to:

scale down the image in the horizontal direction of the image; and

the processor of the image reception unit is further caused to:

scale up the image transmitted from the image transmission unit in the horizontal direction of the image, and

remove aliasing components along the horizontal direction of the scaled-up image based on the calculated angle.

3. The image transfer system according to claim 1 , wherein the processor of the image reception unit is further caused to:

decrease an amount of aliasing components to be removed from the scaled-up image as the calculated angle between the line displayed in the image and the horizontal direction of the image is more vertical, and

increase the amount of the aliasing components to be removed from the scaled-up image as the calculated angle between the line displayed in the image and the horizontal direction of the image is more parallel.

4. The image transfer system according to claim 1 , wherein:

the processor of the image transmission unit is further caused to:

scale down the image by reducing intervals of a frequency at which the image is sampled with a predetermined conversion rate and deleting components other than components within a frequency band included between the frequency for the sampling and a predetermined cut-off frequency, and

transmit the predetermined conversion rate and the predetermined cut-off frequency to the image reception unit; and

the processor of the image reception unit is further caused to:

scale up the image transmitted from the image transmission unit based on the predetermined conversion rate and the predetermined cut-off frequency that have been received,

estimate a frequency that causes the aliasing component based on the predetermined conversion rate and the predetermined cut-off frequency that have been received, and

remove the aliasing component of the scaled-up image based on the estimated frequency and the calculated angle.

5. The image transfer system according to claim 1 , wherein:

the image is an image displayed by progressive scanning;

the processor of the image transmission unit is further caused to:

scale down the image in the horizontal direction and a vertical direction of the image; and

the processor of the image reception unit is further caused to:

scale up the image transmitted from the image transmission unit in the horizontal direction and the vertical direction of the image, and

remove aliasing components along the horizontal direction and the vertical direction of the scaled-up image based on the calculated angle.

6. The image transfer system according to claim 1 , further comprising an image pickup device that picks up an image,

wherein the processor of the image transmission unit processes the image picked-up by the image pickup device and transmits the processed image to the image reception unit.

7. The image transfer system according to claim 1 , wherein:

each of the pixels in the image includes at least one of a brightness component and a color-difference component; and

the processor of the image reception unit is further caused to:

determine one of the brightness component and the color-difference component that corresponds to the each of the pixels,

determine the pixel whose aliasing component is not to be removed and the pixel whose aliasing component is to be removed based on the determined one of the brightness component and the color-difference component, and

remove the aliasing component of the determined pixel whose aliasing component is to be removed.

8. An image transfer method, which is performed by an image transfer system including an image transmission unit that transmits an image and an image reception unit that receives the image transmitted from the image transmission unit, the image transfer method including the steps of:

scaling down, by the image transmission unit, the image;

transmitting, by the image transmission unit, the scaled-down image to the image reception unit;

calculating, by the image reception unit, an angle between a line displayed in the image transmitted from the image transmission unit and a horizontal direction of the image in correspondence with pixels included in the image;

scaling up, by the image reception unit, the image transmitted from the image transmission unit; and

removing, by the image reception unit, an aliasing component of the scaled-up image based on the calculated angle.

9. The image transfer method according to claim 8 , wherein:

the image is an image displayed by interlace scanning;

in the step of scaling down of the image, the image transmission unit scales down the image in the horizontal direction of the image;

in the step of scaling up of the image, the image reception unit scales up the image transmitted from the image transmission unit in the horizontal direction of the image; and

in the step of removing of the aliasing component, the image reception unit removes aliasing components along the horizontal direction of the scaled-up image based on the calculated angle.

10. The image transfer method according to claim 8 , wherein the step of removing of the aliasing component includes the steps of:

decreasing, by the image reception unit, an amount of aliasing components to be removed from the scaled-up image as the calculated angle between the line displayed in the image and the horizontal direction of the image is more vertical; and

increasing, by the image reception unit, the amount of the aliasing components to be removed from the scaled-up image as the calculated angle between the line displayed in the image and the horizontal direction of the image is more parallel.

11. The image transfer method according to claim 8 , wherein:

in the step of scaling down of the image, the image transmission unit scales down the image by reducing intervals of a frequency at which the image is sampled with a predetermined conversion rate and deleting components other than components within a frequency band included between the frequency for the sampling and a predetermined cut-off frequency;

in the step of transmitting of the scaled-down image to the image reception unit, the image transmission unit transmits the predetermined conversion rate and the predetermined cut-off frequency to the image reception unit;

in the step of scaling up of the image, the image reception unit scales up the image transmitted from the image transmission unit based on the predetermined conversion rate and the predetermined cut-off frequency that have been received; and

in the step of removing of the aliasing component, the image reception unit estimates a frequency that causes the aliasing component based on the predetermined conversion rate and the predetermined cut-off frequency that have been received, and removes the aliasing component of the scaled-up image based on the estimated frequency and the calculated angle.

12. The image transfer method according to claim 8 , wherein:

the image is an image displayed by progressive scanning;

in the step of scaling down of the image, the image transmission unit scales down the image in the horizontal direction and a vertical direction of the image;

in the step of scaling up of the image, the image reception unit scales up the image transmitted from the image transmission unit in the horizontal direction and the vertical direction of the image; and

in the step of removing of the aliasing component, the image reception unit removes aliasing components along the horizontal direction and the vertical direction of the scaled-up image based on the calculated angle.

13. The image transfer method according to claim 8 , wherein:

each of the pixels in the image includes one of a brightness component and a color-difference component; and

the step of removing of the aliasing component includes the steps of

determining, by the image reception unit, at least one of the brightness component and the color-difference component that corresponds to the each of the pixels,

determining, by the image reception unit, the pixel whose aliasing component is not to be removed and the pixel whose aliasing component is to be removed based on the determined one of the brightness component and the color-difference component, and

removing, by the image reception unit, the aliasing component of the determined pixel whose aliasing component is to be removed.

14. An image reception apparatus for receiving an image from an image transmission apparatus coupled to the image reception apparatus via a communication line, comprising:

a processor; and

a memory including instructions which cause the processor to:

calculate an angle between a line displayed in the received image which has been scaled down by the image transmission apparatus and a horizontal direction of the image in correspondence with pixels included in the image;

scale up the received image transmitted from the image transmission apparatus; and

remove an aliasing component of the scaled-up image based on the calculated angle corresponding to the pixels.

15. The image reception apparatus according to claim 14 , wherein:

the image comprises an image displayed by interlace scanning; and

the processor is further caused to:

scale up the image, which has been scaled down by the image transmission apparatus in the horizontal direction of the image, in the horizontal direction of the image, and

remove aliasing components along the horizontal direction of the scaled-up image based on the calculated angle.

16. The image reception apparatus according to claim 14 , wherein the processor is further caused to:

scale up the image transmitted from the image transmission apparatus based on a predetermined conversion rate and a predetermined cut-off frequency that have been transmitted from the image transmission apparatus;

estimate a frequency that causes the aliasing component based on the predetermined conversion rate and the predetermined cut-off frequency that have been received; and

remove the aliasing component of the scaled-up image based on the estimated frequency and the calculated angle.

17. The image reception apparatus according to claim 14 , wherein:

the image is an image displayed by progressive scanning; and

the processor is further caused to:

scale up the image, which has been scaled down by the image transmission apparatus in the horizontal direction and a vertical direction, in the horizontal direction and the vertical direction of the image, and

remove aliasing components along the horizontal direction and the vertical direction of the scaled-up image based on the calculated angle.