KR19990032184A - How to rotate black and white image data - Google Patents

Abstract

The present invention relates to a method of rotating black and white image data 90 °, 180 °, 270 ° on a screen, and facilitates processing of black and white image data stored in units of bits using a left and right shift device, a carry bit device, and a left and right rotate device. Allows to rotate the image at high speed.

When rotating the right 90 °, rotate by using the left shift device which shifts one bit to the left and store it in the carry bit and the left rotate device using the contents stored in the carry bit, and when the right 180 ° rotates, the left shift device and the carry bit Rotate the image data 180 ° to the right or left by using the device, right rotate device, and 270 ° or left to the right by using the right shift device, carry bit device, and left rotate device when rotating to the right 270 °. By rotating it by 90 °, the black and white image data stored in bit units can be easily rotated, and it can be rotated at high speed even if the data size is large.

Description

How to rotate black and white image data

The present invention relates to a method of rotating 90 °, 180 °, and 270 ° of left and right monochrome image data input by scanning. In particular, the present invention relates to a high speed shift device and a rotate device for converting monochrome image data stored in bits. The present invention relates to a method of rotating at high speed even with large sized image data.

In general, to scan a document and display its data, it is displayed in a bitmap format, which is a form of an image that can be displayed in a window system. Since these bitmaps do not use a special compression scheme, scanning a single document can be quite large. In particular, in order to process black and white image data stored in one bit per pixel, a bitwise operation must be used. In rotating an image requiring such a bitwise operation, a conventional rotational operation is performed by calculating a bit position of an image to be rotated with the bit position of an original image.

In the conventional method of storing bitmap image data, the number of bits is allocated according to the color per pixel of the screen, and occupies a large amount when expressed at a high resolution. In particular, in the case of black and white bitmap, it is difficult to read and process by byte unit because it requires bit operation. In particular, in the case of an image expressed in high resolution, the number of operations increases.

In order to solve the problems of the prior art as described above, in the present invention, a carry bit device for storing a shifted bit and a carry bit device for storing the shifted bit and the bit loaded in the carry device in the actual CPU. It is an object to make it easy to perform bit-by-bit operations and to rotate image data at high speed by using a rotation apparatus that reads and rotates from side to side.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a diagram showing the position of each bit and the memory pointer change when black and white image data is rotated 90 degrees to the right.

2 is a schematic diagram showing a method of rotating image data 90 ° to the right or 270 ° to the left.

3 is a schematic diagram showing a method of rotating image data 180 ° to the right or left.

4 is a schematic diagram showing a method of rotating image data 270 ° to the right or 90 ° to the left.

Fig. 5 is a flowchart showing a method of rotating image data in accordance with the present invention.

6 is a flowchart showing a method of rotating image data 90 ° to the right or 270 ° to the left.

* Description of the symbols for the main parts of the drawings *

10: raw image memory 11: starting address of raw image memory

12: raw image memory pointer 20: target image memory

21: Start address of the target image memory 22: Target image memory pointer

23: Result memory 31: Left shift (SHL)

32: right shift (SHR) 40: carry

51: left rotator (RCL) 52: right rotator (RCR)

According to an aspect of the present invention, there is provided a method of rotating black and white image data in which a black and white image bitmap data read as a bitmap is rotated by a predetermined angle on a screen, the method comprising: receiving a rotation direction and a rotation angle from a user; Based on the input direction and angle, a raw image memory pointer indicating the start address of the original image to be stored at the start address of the target image memory is designated and read in units of 8 bytes (8 bits x 8 bits) to a temporary 8 byte memory. A reading step of storing; One column (8 bits) or row (8 bits) based on the rotation direction and rotation angle input from the user, starting from the start address indicated by the source image memory pointer of the raw image data stored in the temporary 8 byte memory. Read one byte at a time, shift it to the left or right shift rotator based on the input rotation direction and angle, shift one byte of the rotator to the target image pointer, and store one byte. Rotating 8 bytes repeatedly; The read and rotate steps may be repeatedly rotated and stored in units of 8 bytes with respect to the original image corresponding to the height and width of the entire image by changing the original image memory pointer.

In the present invention, it is important to designate the original image memory pointer differently based on the rotation direction and the angle input from the user.

Therefore, in the present invention, the rightmost bottom left address of the raw image memory is set at the right 90 °, the rightmost bottommost address of the raw picture memory is set at the right 180 °, and the rightmost bottom right address of the raw picture memory is set at the right 270 °. It is specified as the top right address.

When the raw image is rotated 90 degrees to the right (270 degrees to the left), the rotating step starts the address of the leftmost bottom of the raw image memory pointed to by the raw image memory pointer to the raw image data stored in the temporary 8 bytes of memory. After reading one column (8 bits) arranged upward, shift it to the left, shift it to the left rotator, and shift 1 byte of the rotator to the destination image pointer to indicate the starting address indicated by the destination image pointer. Starting with storing one byte in one row (8 bits) arranged to the right, and repeating the above procedure, rotating eight columns of the temporary 8-byte memory by 90 ° to the right to eight rows. It is stored in the target image memory and rotated.

When the original image is rotated 180 degrees to the right (180 degrees to the left), the rotating step includes the bottom right address of the raw image memory pointed to by the raw image memory pointer to the raw image data stored in the temporary 8-byte memory. Starting from, one row (8 bits) arranged in the left direction is read, shifted to the left, shifted to the right rotator, and then shifted by one byte of the rotator to the target image pointer, and the start point indicated by the target image pointer Storing one byte in one row (8 bits) arranged to the right, starting with an address, and repeating the above procedure to rotate eight rows of temporary 8-byte memory by 180 ° to the right The image is stored in the target image memory as a row and rotated.

When the raw image is rotated to the right 270 ° (left 90 °), the rotating step includes the address of the far right uppermost end of the raw image memory pointed to by the raw image memory pointer to the raw image data stored in the temporary 8-byte memory. Starting from, one column (8 bits) arranged downward is read, shifted to the right, shifted to the left rotator, and then shifted one byte of the rotator to the target image pointer, and the starting address indicated by the target image pointer. Storing one byte into one row (8 bits) arranged to the right, starting with. Repeating the above procedure, the eight columns of the temporary 8-byte memory are rotated by 270 ° to the right and eight rows are stored. Rotates it in the target image memory.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 shows an example in which an image is rotated in the present invention, and a data array of a raw image memory 10 expressing a raw image when the raw image before rotation and the original image are rotated by 90 ° to the right. And a data arrangement of the object image memory 20 representing the object image formed by being rotated to the right by 90 °. As shown, it can be seen that the lower left address 11 of the raw image memory corresponds to the start address 21 of the target image memory in the object image rotated to the right by 90 °.

In the present invention, the rotation direction and the angle to be rotated by the user are divided into three cases to perform the rotation operation.

Fig. 2 shows a case where the image data should be rotated 90 degrees to the right or 270 degrees to the left. The original image memory pointer 12 indicating the address of the original image memory and the storage of the rotated image are shown. An objective memory pointer 22 indicating an address to be addressed, a left shift device 31 for shifting the data of the address indicated by the raw image memory pointer 12 by one bit to the left, and a rotated by a predetermined angle A carry bit device 40 in which the left rotate device 51 and a bit shifted to connect them are stored, a result memory 23 in which a rotated one-byte image is stored using these, and data to be used for rotation. S1 to S8 memories are used to perform the data rotation operation of the present invention.

When rotating the original image to the right 90 ° (left 270 °), specify the lowest left address of the memory in which the original image is stored as the start address of the rotating image memory, and rotate the lowest left address of the memory in which the original image is stored. It corresponds to the start address of the picture memory. Therefore, the start byte of the rotated image corresponds to 8 bits b1 to b8 from the bottom left end of the original image data. One byte stored in the row of the rotated image corresponds to a column of eight bytes (S1 to S8) read from the original image. After moving the raw image memory pointer 12 to the leftmost bottom address of the raw image memory, reading one byte to be used for rotation, storing it in S1, and reducing the raw memory pointer 12 by w to perform the operation in the memory. Move, repeat this process 8 times to store 8 bytes from S1 to S8, shift the stored 8 bytes S1 to S8 with left shift to the most significant bit b1 to 1 bit left, and shift with left rotate. To store the resultant carry in the result memory, shifting the most significant bits to the left in order for all the columns of S1 to S8 in the result memory, and storing the rotated image one byte of the rotated image stored in the result memory. After storing in the memory pointed to by the memory pointer 22, the target memory pointer 22 is incremented by 1, and this process is performed from S1 to S8. Performed eight times for the column, and the process to be repeated by the height (h) of the image and the whole image repeatedly rotated by the width (w) of the image the process again.

FIG. 3 shows a case in which the original image is rotated 180 degrees to the right (180 degrees to the left). The bottom right address of the memory in which the original image is stored is designated as the start address of the rotated image memory in which the rotated image is stored. After moving the raw image memory pointer 12 to the far right bottom address of the raw image memory, reading one byte to be used for rotation, storing the result in S1, and reducing the raw memory pointer 12 by one, one byte in memory. Move to the left, repeat this process 8 times to store 8 bytes from S1 to S8, shift the 8-bit stored S1 to S8 with left shift, shift the best bit b1 to 1 bit left, and use right rotate. The shifted carry is stored in the result memory 23, and the process is shifted to the right in order for all the columns b1 to b8 of S1, and the result memory 2 3) and store one byte of the rotated image stored in the result memory 23 in the memory indicated by the object memory pointer 22 for storing the rotated image, and then increase the object memory pointer 22 by one. The process is performed eight times from S1 to S8, and this process is repeated by the width w of the image and this process is repeated by the height h of the image so that the entire image is rotated.

The address at the bottom right of the memory in which the original image is stored is converted to the start address of the rotated image memory. When the rotation angle is 180 °, one byte of row data of the original image is stored as row data even in the rotated image. So you can read them one byte at a time. However, because it is rotated 180 °, the bit column within one byte read is reversed. This problem uses a left shift device to rotate the bits shifted to the left to the right to reverse the bit string, store them in the result memory 23 and store them at the address indicated by the destination memory pointer 22.

FIG. 4 illustrates a case in which a raw image is rotated to the right 270 ° (left 90 °), and the top right address of the memory in which the raw image is stored is designated as the start address of the rotated image memory, and the start image memory pointer ( 12), read one byte for rotation and store it in S8, then increase the raw memory pointer 12 by width (w) to move down one row in memory, repeating this process eight times Stores 8 bytes from S1 to S1, shifts the least significant bit b1 to right by 1 bit using right shift, and stores the shifted carry to result memory using left rotate. The process shifts the least significant bits to the right in order for all the columns of S1 to S8 and stores them in the result memory 23, and the rotated image one byte stored in the result memory 23 After storing the rotated image in the memory pointed to by the object memory pointer 22, the object memory pointer 22 is increased by one, this process is performed eight times for all the columns of S1 to S8, and the process is performed. Repeat (h) and repeat this process by the width w of the image so that the entire image is rotated.

The same applies to the rotation of 90 ° to the left due to the nature of the rotation. When rotating 270 ° to the right, the address of the far rightmost top of the memory in which the original image is stored corresponds to the start address of the rotated image memory. As shown in Fig. 4, the combination of the respective bit strings of 8 bytes (S1 to S8) read from the far right uppermost address of the raw image memory to the bottom is stored as one byte of the rotated image. In this case, since the least significant bit b1 becomes the start of the rotated image from S8, the left carry bit is shifted to the right, and the stored carry bit is rotated to the left to fill the result memory 23 with 8 bits and stored at the address indicated by the destination memory pointer 22. do.

5 shows an overall flowchart for rotating image data 90 °, 180 °, 270 ° to the right or left.

First, the rotation direction and the rotation angle of the image are input (61). According to the input rotation direction and the rotation angle, the operation branches to right 90 °, right 180 °, and right 270 ° (62). Each is equal to the left 270 °, 180 °, 90 ° rotation in the characteristic of 90 ° rotation. When the branch is determined according to the input value, the raw memory pointer 12 value corresponding to each branch is calculated (63, 64, 65). That is, in the left 90 ° rotation, the rightmost top address (w-1) of the raw memory becomes the raw memory pointer 12 value (63), and in the left 180 ° rotation, the rightmost bottom address ((h * w) -1) is the value of the raw memory pointer 12 (64), and when the left is rotated 270 °, the lowest left address (w * (h-1)) becomes the raw memory pointer 12 and rotated. Let's start with the method. In this way, after calculating the raw address according to each branch, when the rotation is 90 ° left, the rotation is performed by using the right shift 32, the carry 40, and the left rotate 51 (66), and the rotation is 180 ° left. Use the left shift 31, the carry 40, and the right rotate 52 (67), and rotate the image using the left shift 41 and the left rotate 52 (68) when rotating left 270 ° (68). By storing the rotated image data in the object memory, the rotated image is obtained.

6 is a flowchart for rotating image data 90 ° to the right as an embodiment of the present invention, which will be described in detail as follows.

This embodiment is equally applicable to the left 270 ° rotation. After moving to the original memory pointer 12 described in FIG. 5, one byte to be used for rotation is read and stored in S1, and then the original memory pointer 12 is reduced by w to move to an action in the memory (101). This process is repeated eight times to store eight bytes from S1 to S8 first (102). The left 8 shifts S1 to S8, which are stored, shift the most significant bit b1 1 bit to the left (103), and the shifted carry is stored in the result memory using the left rotate. This process shifts the most significant bits to the left in order for all columns of S1 to S8 (105) and stores them in the result memory. The resultant memory 23 has a byte of rotated images, which are stored in the memory pointed to by the object memory pointer 22 and then incremented by one (106). This process (103, 104, 105, 106) is performed eight times for all the columns of S1 to S8 (107). When 8 bytes are completed, the target memory pointer is decreased by w * 8, and then increased by 1, and this process (101 to 107) is repeated by h of the image, and this process (101 to 108) is repeated by w of the image. Performing while increasing the memory pointer of an image by ((h-1) * w) +1 of the image causes the entire image to rotate.

As described above, when the image rotation performance according to the present invention is compared with that of the conventional image rotation method, it has been conventionally performed to store the image data of the original image at the address indicated by the target image pointer for each bit. According to the present invention, the rotation operation is performed by binding 8 bytes to reduce the overall processing time, and the shift unit and the rotation unit that can be operated in units of bits, and the monochrome unit composed of bits using a carry bit unit connecting the same Bitmap image data can be easily processed, and the two devices used can be rotated at high speed due to similarity with hardware devices. Therefore, black and white bitmap image data expressed in high resolution can be easily processed in units of bits, and it is possible to rotate at a high speed even for a large amount of data.

Claims (5)

In the method for rotating the black and white image bitmap data stored in the bitmap form in a predetermined direction on the screen by a predetermined angle, Receiving a rotation direction and rotation angle from a user; Based on the input direction and angle, a raw image memory pointer indicating the start address of the original image to be stored at the start address of the target image memory is designated and read in units of 8 bytes (8 bits x 8 bits) to a temporary 8 byte memory. A reading step of storing; One column (8 bits) or row (8 bits) based on the rotation direction and rotation angle input from the user, starting from the start address indicated by the source image memory pointer of the raw image data stored in the temporary 8 byte memory. Read one byte at a time, shift it to the left or right shift rotator based on the input rotation direction and angle, shift one byte of the rotator to the target image pointer, and store one byte. Rotating 8 bytes repeatedly; And changing the original image memory pointer to rotate and store the read and rotate steps in 8 byte units for the original image corresponding to the height and width of the entire image. The method of claim 1, The designated raw image memory pointer is In case of right side 90 °, it is regarded as the lowest left address of the raw image memory. If it is 180 ° to the right, it is set as the lowest right address of the raw image memory. And 270 ° to the right, the black and white image data rotating method as specified by the address at the top right of the raw image memory. The method of claim 2, If you rotate the original image 90 ° to the right (270 ° to the left), The rotating step, The raw image data stored in the temporary 8-byte memory is shifted to the left by reading one column (8 bits) arranged in the upward direction, starting with the lowest leftmost address of the raw image memory indicated by the raw image memory pointer. After shifting to the left rotator, one byte of the rotator is shifted to the target image pointer, and one byte is stored in one row (8 bits) arranged to the right starting from the start address indicated by the target image pointer. Steps; Repeating the above steps to rotate the eight columns of the temporary 8-byte memory by 90 ° to the right, storing them in the target image memory in eight rows, and rotating them. The method of claim 2, When rotating the original image to the right 180 ° (left 180 °), The rotating step, The raw image data stored in the temporary 8-byte memory is shifted to the left by reading one row (8 bits) arranged leftward, starting with the address at the far right bottom of the raw image memory indicated by the raw image memory pointer. After shifting to the right rotator, one byte of the rotator is shifted to the target image pointer to store one byte in one row (8 bits) arranged to the right starting from the start address indicated by the target image pointer. Steps; And repeating the above steps, rotating eight rows of the temporary 8-byte memory by 180 ° to the right, storing the eight rows of the temporary 8-byte memory in the target image memory, and rotating them. The method of claim 2, If you rotate the original image to the right 270 ° (left 90 °), The rotating step, The raw image data stored in the temporary 8-byte memory starts with the address of the far rightmost top of the raw image memory pointed to by the raw image memory pointer, and reads one column (8 bits) arranged downward and shifts it to the right. Shifting the left rotator to the target image pointer and storing one byte in one row (8 bits) arranged to the right starting from the start address indicated by the target image pointer. Wow; Repeating the above steps to rotate the eight columns of the temporary 8-byte memory to the right by 270 °, storing them in the target image memory in eight rows, and rotating them.