The present invention relates to an image display device, and more particularly, to an image display device displaying, on an enlarged or reduced scale, document images containing characters, pictures or photographs, or the like.
Simply enlarging or reducing an image in its entirety has been generally known as a technique for displaying a document image containing pictures, photographs or the like in an enlarged or reduced scale with a display device. A technique is also generally known and is employed in a word processor or a WWW (Word Wide Web) browser wherein the number of characters per line is changed depending on a size of a display screen or print sheet, and characters and pictures are rearranged for displaying or printing.
Further, in connection with document images formed of image data, a method has been known for distinguishing and extracting character regions in the document image from non-character regions, as is disclosed in Japanese Patent Laying-Open No. 9-16713. Another method is also known for extracting regions of main body or text from image data, and arranging the extracted main body regions in units each formed of a line or a block, as is disclosed in Japanese Patent Laying-Open No. 5-328097.
When one reads pages of a book, characters may be excessively small and difficult to read. If a method of simply enlarging the whole image is employed in the above case, the enlarged or reduced image may be larger than the display screen so that some characters may fall out of a display screen.
For viewing the undisplayed portion, a scroll bar may be arranged in an image display device for manipulation. However, manipulation for vertically or horizontally moving the image is required, resulting in low operability.
For zooming in or out (i.e., enlarging or reducing) only a required portion in the image, it is necessary to specify a rate of zooming in or out (which will be referred to as a xe2x80x9czoom ratexe2x80x9d, hereinafter) every time the zooming is required. Further, the zoom rate must be changed in accordance with every change in page layout of the page of the book. This impairs the operability.
If a vertically or horizontally long image is zoomed out to display the whole image within the display screen, regions not displaying the image are formed vertically or horizontally in the display screen. This prevents effective use of the display screen, and reduces an amount of information displayed on the screen.
According to the method disclosed in Japanese Patent Laying-Open No. 5-328097, since rearrangement is performed in units each formed of a line or a block, the number of characters per line cannot be set to an arbitrary value. If the picture or photograph regions are present together with the character regions in a mixed fashion, it is impossible to display both kinds of regions in appropriate sizes.
Accordingly, an object of the invention is to provide an image display device that can display a zoomed (i.e., enlarged or reduced) image with good operability.
Another object of the invention is to provide an image display device that can zoom in or out an input image while keeping a large amount of information displayed on each output image.
Yet another object of the invention is to provide an image display device that can zoom in or out picture or photograph regions as well as character regions at appropriate zoom rates even if these regions are mixedly present in a single input image.
Further another object of the invention is to provide an image display device that can display a page number and others to be located in a peripheral region of an input image in appropriate positions on an output image prepared by enlarging an input image.
According to an aspect of the invention, an image display device includes a divided line region extracting portion for dividing a line region included in an input image in a line direction, and extracting a plurality of divided line regions, and a processing portion connected to the divided line region extracting portion for zooming in or out, arranging and displaying the divided line regions at a predetermined zoom rate in units each formed of the extracted divided line region while keeping a sequence of arrangement.
Since zooming is performed in units each formed of the divided line region prepared by dividing the line region of the input image, text can be zoomed in or out without disturbing a sequence of characters in the input image. By appropriately determining a length of one side of the output image, therefore, a user can read the text only moving the output image only in one direction so that the user can easily view the document image. Since the rearrangement is performed for each divided line region, an amount of information which can be displayed on each output image can be larger than that on an output image prepared by merely enlarging the input image.
Preferably, when the divided line regions cannot be displayed in an output image of a predetermined size, the processing portion prepares a new output image for arranging the divided line region thereon.
When the divided line region cannot be displayed in a single output image, they are output as a plurality of continuous output images. The output image has the predetermined size. Therefore, the user can successively view the displayed contents by switching output images, resulting in improved operability.
More preferably, the image display device includes a picture region detecting portion for detecting a picture region and a photograph region in the input image, and a picture zoom rate calculating portion connected to the picture region detecting portion for determining a new zoom rate in relation to the predetermined zoom rate for zooming the picture and photograph regions detected by the picture region detecting portion so as to prevent increase in size over the output image. The divided line region extracting portion is connected to the picture region detecting portion for extracting as the divided line regions the picture region and the photograph region detected by the picture region detecting portion. The processing portion includes a picture zooming and displaying portion connected to the divided line region extracting portion and the picture zoom rate calculating portion for zooming in or out, and arranging the picture region and the photograph region based on the new zoom rate for display on the output image, and a character zooming and displaying portion connected to the divided line region extracting portion for zooming in or out, and arranging the divided line region other than the picture region and the photograph region based on the predetermined zoom rate for display on the output image.
When the picture region and the photograph region are zoomed in or out, the zoom rate of the picture region and the photograph region is determined to prevent increase in size over the output image. This zoom rate is different from that of the character portion. Therefore, the user can view the picture and photograph regions and the text which are appropriately zoomed in or out without extending off the screen.
More preferably, the image display device further includes a picture region detecting portion for detecting the picture region and the photograph region in the input image, and an output image size calculating portion connected to the picture region detecting portion for comparing a size of the picture region or the photograph region detected by the picture region detecting portion and zoomed in or out at the predetermined zoom rate with a size of the output image, and selecting the larger size as a new output image size. The processing portion further includes a picture zooming and displaying portion connected to the region detecting portion, the divided line region extracting portion and the output image size calculating portion for zooming in or out, and arranging the picture region and the photograph region based on the predetermined zoom rate for display in a position on the output image determined based on the new output image size, and a character zooming and displaying portion connected to the region detecting portion, the divided line region extracting portion and the output image size calculating portion for zooming in or out, and arranging the picture region and the photograph region based on the predetermined zoom rate for display in a position on the output image determined based on the original output image size.
The size of the output image is determined depending on the sizes of the picture region and the photograph region which are zoomed in or out. Therefore, a user can freely designate the zoom rates of the picture region and the photograph region. Further, the size of the original output image may be determined to be equal to that of the display region, whereby the scrolling in only one direction is required for reading the text.
More preferably, the image display device further includes a body peripheral region detecting portion connected to the divided line region extracting portion for detecting, as a body peripheral region, the divided line region located on an end of the input image among the divided line regions. The processing portion is connected to the body peripheral portion detecting portion and the divided line region extracting portion for arranging and displaying the body peripheral region while keeping the same relative positional relationship as that on the input image.
This can avoid such a disadvantage that the body peripheral region and the other regions are zoomed in or out without distinguishing them from each other, and thereby a page number and others are displayed in unexpected positions.
An image display device according to another aspect of the invention includes a body region extracting portion for extracting a body region other than an end of each of a plurality of input images, a zoom rate calculating portion connected to the body region extracting portion for calculating a zoom rate for each of the plurality of input images such that the enlarged body region has the same size as the input image, a common zoom rate determining portion connected to the zoom rate calculating portion for determining a common zoom rate based on the output of the zoom rate calculating portion, and a processing portion connected to the body region extracting portion and the common zoom rate determining portion for enlarging and displaying the body region of each of the plurality of input images at the common zoom rate.
The zoom rate common to the input images is determined. Therefore, characters of a substantially uniform size can be displayed on the different output images, and a user can read the text without a sense of incompatibility.