Image expansion and display method, image expansion and display device, and program for image expansion and display
View Patent ↗A header information analysis section analyzes header information of a compressed image file and reads an original image size while comparing the read original image size and an image size required for display and performing an operation of a size ratio. A JPEG expansion section expands image data of the image file by MCU. A resizing section magnifies or reduces by MCU the image data expanded by the JPEG expansion section according to the size ratio obtained by the header information analysis section and transfers the magnified or reduced data to a display frame memory.
1. A method for expanding a JPEG compressed image file to display it on a display unit, the method comprising:
a first step of analyzing header information of the image file and reading an original image size;
a second step of comparing the original image size read in the first step and an image size required for display on the display unit and performing an operation of a size ratio;
a third step of expanding image data of the image file by MCU;
a fourth step of magnifying or reducing by MCU the image data expanded in the third step according to the size ratio obtained in the second step; and
a fifth step of storing the image data obtained in the fourth step in a display frame memory,
wherein the third through fifth steps are repeatedly executed for the whole image file and then the image data stored in the display frame memory is supplied to the display unit and the fourth step is performed without recording an expanded whole image in a memory.
2. The method of claim 1 , wherein in the fourth step, a zooming function is used.
3. The method of claim 1 , wherein in the fourth step, thinning-out or interpolation of the image data is used.
4. A device for expanding a JPEG compressed image file to display it on a display unit, the device comprising:
a header information analysis section for analyzing header information of the image file and reading an original image size while comparing the read out original image size and an image size required for display on the display unit and performing an operation of a size ratio;
a JPEG expansion section for expanding image data of the image file by MCU; and
a resizing section for magnifying or reducing by MCU the image data expanded by the JPEG expansion section according to the size ratio obtained by the header information analysis section and transferring the magnified or reduced image data to a display frame memory,
wherein the image data expanded by the JPEG expansion section is magnified or reduced by the resizing section without recording an expanded whole image in a memory.
5. A computer-readable medium storing a program for causing a computer to perform the function of expanding a JPEG compressed image file to display it on a display unit,
wherein the program, when executed by the computer, causes the computer to perform:
a first function of analyzing header information of the image file and reading an original image size,
a second function of comparing the original image size read by the first function and an image size required for display on the display unit and performing an operation of a size ratio,
a third function of expanding image data of the image file by MCU, and
a fourth function of magnifying or reducing by MCU the image data expanded by the third function according to the size ratio obtained by the second function and transferring the magnified or reduced image data to a display frame memory,
wherein the image data expanded by the third function is magnified or reduced without recording an expanded whole image in a memory.