Multi-layer image mixing apparatus
First Claim
1. A multi-layer image mixing apparatus for creating a composite image from multiple image layers, the apparatus comprising:
- an image memory;
input means for sequentially inputting image fractions of the multiple image layers from foremost through rearmost ones, each said image fraction being located at the same position in associated one of the layers and having a size of one frame or less;
initializing means for initializing the image memory by storing the image fraction of the rearmost layer in the image memory;
mixing means for performing the process steps of a) mixing one of the image fractions that was stored previously in the image memory with another one of the image fractions that has just been input by calculating a weighted average of these two image fractions and b) storing the newly mixed image fraction in the image memory, the mixing means repeatedly performing these process steps a) and b) until the mixing means has processed the image fraction of the foremost layer;
output means for outputting a combined image fraction that has been finally stored in the image memory by the mixing means; and
control means for making the input, initializing, mixing and output means perform their processes continuously until the last image fraction of the foremost layer has been processed.
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Abstract
After having stored one line of a rearmost layer in an image memory, a mixer repeatedly performs an image mixing process until the mixer has processed one line of a foremost layer. The mixing process includes the steps of: mixing one line previously stored in the image memory with another line that has just been input by calculating a weighted average of these two lines; and storing the newly mixed line in the image memory. As a result of this repetitive process performed by the mixer, a combined line, which has been stored finally in the image memory, is output to a display monitor. The mixer will continuously operate until the mixer has processed the last line of the foremost layer. Semitransparent mixing of multiple layers is implementable using a small-sized image memory for image mixing. In addition, where the image memory is made up of first and second line memories each having a storage capacity of one line, display operation and mixing process can be executed concurrently.
75 Citations
6 Claims
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1. A multi-layer image mixing apparatus for creating a composite image from multiple image layers, the apparatus comprising:
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an image memory;
input means for sequentially inputting image fractions of the multiple image layers from foremost through rearmost ones, each said image fraction being located at the same position in associated one of the layers and having a size of one frame or less;
initializing means for initializing the image memory by storing the image fraction of the rearmost layer in the image memory;
mixing means for performing the process steps of a) mixing one of the image fractions that was stored previously in the image memory with another one of the image fractions that has just been input by calculating a weighted average of these two image fractions and b) storing the newly mixed image fraction in the image memory, the mixing means repeatedly performing these process steps a) and b) until the mixing means has processed the image fraction of the foremost layer;
output means for outputting a combined image fraction that has been finally stored in the image memory by the mixing means; and
control means for making the input, initializing, mixing and output means perform their processes continuously until the last image fraction of the foremost layer has been processed. - View Dependent Claims (2, 3, 4, 5, 6)
wherein a frame, which is made up of the combined image fractions that have been sequentially output from the image memory, is presented on a raster-scan display device. -
3. The apparatus of claim 1, wherein the mixing means comprises:
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means for inputting an opacity, the opacity being represented as a value between zero and one;
first multiplication means for multiplying together a pixel value of each said input image fraction and the opacity;
second multiplication means for multiplying together a value of an associated pixel in the image fraction stored in the image memory and a value obtained by subtracting the opacity from one; and
adding means for adding together products obtained by the first and second multiplication means, wherein a sum obtained by the adding means is stored in the image memory.
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4. The apparatus of claim 1, wherein the image memory comprises first and second memories each having an equal storage capacity, and
wherein while the combined image fraction that has been finally stored in the first memory is being output, the mixing means repeatedly performs the mixing process using the second memory, and while the combined image fraction that has been finally stored in the second memory is being output, the mixing means repeatedly performs the mixing process using the first memory. -
5. The apparatus of claim 1, wherein the image memory comprises first and second half-memories each having a storage capacity corresponding to half of the image fraction, and
wherein while a pixel is being read out from the first half-memory to the mixing means, another pixel is written on the second half-memory, and while a pixel is being read out from the second half-memory to the mixing means, another pixel is written on the first half-memory. -
6. The apparatus of claim 5, further comprising a delay circuit interposed between the mixing means and the image memory,
wherein the number of latches included in the delay circuit is equal to the number of pixels that is readable successively from the first and second half-memories and to the number of pixels that is writable successively on the first and second half-memories.
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Specification