Moving image display device and moving image display method
View Patent ↗To provide a technology for performing brightness range expansion processing suitable for a scene change when a scene change occurs. If an expansion coefficient output mode determination module 250 detects a scene change, it changes an expansion coefficient output mode from a normal mode to a scene change mode. An expansion coefficient derivation module 200 outputs an ideal expansion coefficient Gid(n) if the scene change is detected, and outputs a corrected expansion coefficient G(n) if the scene change is not detected.
1. A moving image display apparatus that displays moving images based on moving image data, comprising:
an illumination device;
a light modulation coefficient derivation module that, based on an image feature amount pertaining to a brightness of image data for one frame of the moving image data, derives and outputs a light modulation coefficient to be used to modulate a light amount emitted by the illumination device, for each frame of the moving image data;
a light modulation module that performs light modulation for the illumination device based on the light modulation coefficient output by the light modulation coefficient derivation module; and
a scene change detector that detects a scene change indicating that a scene in the moving image has changed, the scene change detector detecting a start of a scene change when a specified scene change start condition is satisfied and detecting an end of the scene change when a specified scene end condition different from the scene change start condition is satisfied, so as to detect the start to the end of the scene change as the scene change, wherein
if the scene change is detected, the light modulation coefficient derivation module outputs a current-frame ideal light modulation coefficient that is determined according to the image feature amount for the current frame, and
if the scene change is not detected, the light modulation coefficient derivation module outputs a current-frame corrected light modulation coefficient that is obtained by correcting the current-frame ideal light modulation coefficient based on a predetermined rule.
2. A moving image display apparatus according to claim 1 , wherein the light modulation coefficient derivation module determines the current-frame corrected light modulation coefficient such that an absolute value of a corrected light modulation coefficient difference is smaller than an absolute value of an ideal light modulation coefficient difference and a sign of the corrected light modulation coefficient difference is the same as a sign of the ideal light modulation coefficient difference, wherein
the ideal light modulation coefficient difference is obtained by subtracting a previous-frame actual light modulation coefficient from the current-frame ideal light modulation coefficient, the previous-frame actual light modulation coefficient being a light modulation coefficient used by the light modulation module for the light modulation for a previous frame, and
the corrected light modulation coefficient difference is obtained by subtracting the previous-frame actual light modulation coefficient from the current-frame corrected light modulation coefficient.
3. A moving image display apparatus according to claim 1 , wherein the light modulation coefficient derivation module,
(i) after the scene change is detected, outputs the current-frame ideal light modulation coefficient until a predetermined stop condition is satisfied, and
(ii) after the stop condition is satisfied, outputs the current-frame corrected light modulation coefficient.
4. A moving image display apparatus according to claim 3 , wherein the stop condition includes at least one of following conditions: (a) a difference between the current-frame corrected light modulation coefficient and the current-frame ideal light modulation coefficient is equal to or smaller than a predetermined threshold value, and (b) the current-frame ideal light modulation coefficient is greater than a previous-frame ideal light modulation coefficient derived for a previous frame by the light modulation coefficient derivation module.
5. A moving image display apparatus according to of claim 1 , wherein the scene change detector detects the scene change if a start condition is satisfied, the start condition including a condition 1 holding that a white peak value representing a maximum brightness value of the image data is equal to or smaller than a predetermined threshold value.
6. A moving image display apparatus according to claim 5 , wherein the start condition is satisfied if both of the condition 1 and a condition 2 are satisfied, the condition 2 holding that a difference between the current-frame corrected light modulation coefficient and the current-frame ideal light modulation coefficient is greater than a predetermined value.
7. A moving image display apparatus according to claim 1 , wherein
the image feature amount includes a plurality of image feature amounts obtained with respect to a brightness histogram of the image data, and
the light modulation coefficient derivation module derives the ideal light modulation coefficient with reference to a preset light modulation coefficient lookup table using the plurality of image feature amounts.
8. A projector comprising:
an illumination device;
a light modulation coefficient derivation module that, based on an image feature amount pertaining to a brightness of image data for one frame of the moving image data, derives and outputs a light modulation coefficient to be used to modulate a light amount emitted by the illumination device, for each frame of the moving image data;
a light modulation module that performs light modulation for the illumination device based on the light modulation coefficient output by the light modulation coefficient derivation module; and
a scene change detector that detects a scene change indicating that a scene in the moving image has changed, the scene change detector detecting a start of a scene change when a specified scene change start condition is satisfied and detecting an end of the scene change when a specified scene end condition different from the scene change start condition is satisfied, so as to detect the start to the end of the scene change as the scene change, wherein
if the scene change is detected, the light modulation coefficient derivation module outputs a current-frame ideal light modulation coefficient that is determined according to the image feature amount for the current frame and
if the scene change is not detected, the light modulation coefficient derivation module outputs a current-frame corrected light modulation coefficient that is obtained by correcting the current-frame ideal light modulation coefficient based on a predetermined rule.
9. A projector in accordance with claim 8 , wherein the illumination device includes:
a discharge lamp; and
a light modulation element controls power supplied to the discharge lamp base on a parameter corresponding to the light modulation coefficient.
10. A projector in accordance with claim 9 , wherein the light modulation module calculates a value of the light amount which indicates a percentage of the maximum light amount based on the light modulation coefficient and output the value of the light amount to the illumination device as the parameter.
11. A moving image display method that displays moving images based on moving image data using an illumination device, comprising the steps of:
(a) based on an image feature amount pertaining to a brightness of image data for one frame of the moving image data, deriving and outputting a light modulation coefficient to be used to modulate a light amount emitted by the illumination device, for each frame of the moving image data;
(b) performing light modulation for the illumination device based on the light modulation coefficient output in step (a); and
(c) detecting a scene change indicating that a scene in the moving image has changed, including detecting a start of a scene change when a specified scene change start condition is satisfied and detecting an end of the scene change when a specified scene end condition different from the scene change start condition is satisfied, so as to detect the start to the end of the scene change as the scene change, wherein
the step (a) includes,
if the scene change is detected, outputting a current-frame ideal light modulation coefficient that is determined according to the image feature amount for the current frame, and
if the scene change is not detected, outputting a current-frame corrected light modulation coefficient that is obtained by correcting the current-frame ideal light modulation coefficient based on a predetermined rule.
12. A moving image display apparatus that displays moving images based on moving image data, comprising:
an illumination device;
a light modulation coefficient derivation module that, based on an image feature amount pertaining to a brightness of image data for one frame of the moving image data, derives and outputs a light modulation coefficient to be used to modulate a light amount emitted by the illumination device, for each frame of the moving image data;
a light modulation module that performs light modulation for the illumination device based on the light modulation coefficient output by the light modulation coefficient derivation module; and
a scene change detector that detects a scene change indicating that a scene in the moving image has changed, wherein
if the scene change is detected, the light modulation coefficient derivation module outputs a current-frame ideal light modulation coefficient that is determined according to the image feature amount for the current frame, and
if the scene change is not detected, the light modulation coefficient derivation module outputs a current-frame corrected light modulation coefficient that is obtained by correcting the current-frame ideal light modulation coefficient based on a predetermined rule; and
the light modulation coefficient derivation module determines the current-frame corrected light modulation coefficient such that an absolute value of a corrected light modulation coefficient difference is smaller than an absolute value of an ideal light modulation coefficient difference and a sign of the corrected light modulation coefficient difference is the same as a sign of the ideal light modulation coefficient difference,
the ideal light modulation coefficient difference is obtained by subtracting a previous-frame actual light modulation coefficient from the current-frame ideal light modulation coefficient, the previous-frame actual light modulation coefficient being a light modulation coefficient used by the light modulation module for the light modulation for a previous frame, and
the corrected light modulation coefficient difference is obtained by subtracting the previous-frame actual light modulation coefficient from the current-frame corrected light modulation coefficient.