Image analysis – Image transformation or preprocessing – Changing the image coordinates
Reexamination Certificate
1998-09-16
2002-09-24
Couso, Jose L. (Department: 2621)
Image analysis
Image transformation or preprocessing
Changing the image coordinates
C382S276000
Reexamination Certificate
active
06456745
ABSTRACT:
TECHNICAL FIELD OF THE INVENTION
This invention relates to video signal processing and more particularly to a method and system for re-sizing images and zooming into and out of images in a way that makes use of non-spatial interpretations of the images.
BACKGROUND OF THE INVENTION
Images can be imported into digital systems using opto-electronic transducing devices, such as video cameras and computer scanning devices. Also, images can be created within digital systems using a variety of computer software programs, such as drawing and animation programs. Images are commonly represented and stored in digital systems as arrays of digital numbers.
Images are typically displayed on a suitable display device, such as the cathode ray tube (“CRT”) of a television or computer monitor, as a two-dimensional spatial representation on the surface of the display device. A series of slightly different images can be displayed in rapid temporal sequence in order to create the perception of smooth motion as, for example, in the case of television image sequences.
Pixels are relatively small localized fixed regions on the surface of the image display device. Displayed images are often composed of many thousands of pixels, wherein each pixel has attributes of size, shape, intensity and color. Objects within displayed images are represented by groups of pixels. Generally, the pixels are sufficiently close to each other on the surface of the display device to ensure that when the displayed image is viewed from a sufficient distance objects are perceived to have the same characteristics of shape, texture, edges and shading as similar objects in the real world.
Pixels are often, but not always, arranged on the surface of the display in the form of a rectangular grid consisting of uniform rows and columns of pixels. The horizontal and vertical spatial resolutions of an image are determined by the average number of pixels per unit of distance in the horizontal direction along the rows of pixels and in the vertical direction along the columns of pixels. The spatial resolution determines the minimum distance at which an image must be viewed so that the human vision system (“HVS”) perceives objects within the image and not the individual pixels.
The spatial resolution of a displayed image can be increased by increasing the horizontal resolution and the vertical resolution. A high resolution image will yield a more natural looking approximation of an original real world image than a low resolution image. The quality of the image results from the HVS's perception of the lines and edges within displayed images. In low resolution images, the lines and edges are often perceived to be jagged because of the staircase effect caused by rectangular-shaped pixels in the displayed image.
The perception of jagged edges and lines, due to the staircase effect, is less discernible in high resolution images because of the reduced size of the rectangular-shaped pixels in the displayed image.
The finite resolution of the displayed image is a major factor limiting the faithfulness by which objects may be represented.
A digital image is a set of numbers where each number corresponds to a pixel of the displayed image. For example, a displayed image might consist of 512 by 640 pixels where each pixel is characterized by a range of possible luminous intensities and colors. If we decompose the color of each pixel into its primary colors of red (“R”), blue (“B”) and green (“G”), then the displayed image may be numerically represented as the combination of the R, B and G component images. Each of the R, B and G component images is a monochromatic image in which each pixel is characterized only by a digital number representing the luminous intensity of the pixel. A displayed image, consisting of a rectangular array of pixels, may therefore be represented as three monochromatic component images, each of which may be represented in digital form as a corresponding rectangular array of numbers. We refer to such a rectangular array of numbers as a digital image where it is understood that it may represent a monochromatic component of a displayed color image or some suitable combination of the monochromatic components.
An image display device has a fixed viewing area which is usually a rectangular viewing screen. Images displayed on the viewing screen often completely fill the viewing screen. Re-sizing of the image means that the image is re-displayed on the viewing screen in such a way that the image is perceived by the HVS to have been horizontally or vertically stretched or compressed. The ratio of the horizontal size of the image after re-sizing to the horizontal size before re-sizing is the horizontal scaling factor. Similarly, the vertical scaling factor is the ratio of the vertical size of the image after re-sizing to the vertical size before re-sizing. Scaling factors greater than unity represent stretching and scaling factors less than unity represent shrinking of a displayed image.
The aspect ratio of a displayed image is the ratio of its width to its height. If the image is resized using equal horizontal and vertical scaling factors, then the resized image will have the same aspect ratio as the original. By using equal horizontal and vertical scaling factors, objects will grow or shrink without changing their shapes and the re-sizing operation will be perceived by the HVS as having caused all objects within the image to have moved closer to or farther away from the viewer.
Resized images may exceed the dimensions of the viewing screen. Thus, some parts of the resized image may lie outside of the viewing screen and may not be visible. A cropped image is that portion of the image that is displayed in the viewing screen.
Zooming is the re-sizing of a set of digitized images or displayed images to create the perception in the HVS that objects within the displayed image are growing or shrinking with time. Zooming creates the illusion that the distances between the viewer and the objects in the displayed image are growing or shrinking.
Smooth zooming is zooming such that the scaling factors increase or decrease sufficiently slowly over the set of displayed images to create the perception in the HVS that objects within the displayed image are growing or shrinking continuously with time during the process of zooming.
If the scaling factors are increasing with time the zooming process is in the zoom-in mode and if the scaling factors are decreasing with time the zooming process is in the zoom-out mode. For example, a smooth zoom in the zoom-in mode can be achieved in 11 successive frames having scale factors, relative to the first frame, of 1.0, 1.1, 1.2 . . . 1.8, 1.9 and 2.0, resulting in the final scaling factor of 2.
Prior art methods for re-sizing and zooming digitized images operate directly on the numbers which represent each of the pixels in the displayed image. That is, they operate in the spatial domain.
One prior art method of re-sizing images is the pixel replication method which uses integer scale factors. The pixel replication method simply copies each pixel some integer number of times in both the horizontal and vertical directions. For example, with a scaling factor of 3, each pixel of the original image is replicated to form a corresponding 3×3 square of pixels in the resized image. A primary disadvantage of pixel replication methods is that the jagged staircase effects of the pixelization increase in proportion to the scaling factor. Thus, pixel replication introduces significant and often unacceptable distortion of the image after re-sizing. A further disadvantage of the pixel replication method is that it is limited to enlarging images by integer scaling factors. Therefore, it cannot be used to reduce the size of the image, nor can it be used to re-size an image by non-integer scale factors, such as 1.1, 1.2, etc., as required for smooth zooming operations.
Another prior art method is the pixel sub-sampling method, which is used to reduce the size of images using scaling factors that are the reciprocals o
Bruton Leonard Thomas
Simpson Todd
Yee Barry
Couso Jose L.
Patel Kanji
Push Entertaiment Inc.
LandOfFree
Method and apparatus for re-sizing and zooming images by... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method and apparatus for re-sizing and zooming images by..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method and apparatus for re-sizing and zooming images by... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2838750