Image processing method and image coding apparatus utilizing the image processing method
A wavelet transform is applied to an original image, so as to generate an image of a first hierarchy. Among the thus generated image of the first hierarchy, each of high-frequency sub-band components 1HL, 1LH and 1HH are immediately quantized and coded so as to be temporarily stored in a coded data storage. Another wavelet transform is applied to an LL sub-band component, among the image of the first hierarchy, so as to generate an image of a second hierarchy. Thereafter, an image of a third hierarchy is generated from an LL sub-band component in the image of the second hierarchy. During such a process, quantization and coding processings are performed in parallel with transformation processings. After all processings are completed and the coded data are prepared, coded image data complying with the JPEG2000 standard are generated by first reading out low-frequency components in sequence from the prepared coded data.
1. An image processing method, including:
converting an image to spatial frequency components; and
quantizing the spatial frequency components obtained by said converting,
wherein said converting performs a conversion processing that is of a form such that low frequency components of the image are obtained at a subsequent processing stage, and
wherein said quantizing is such that, during a processing by said converting, every time higher spatial frequency components are obtained, the thus obtained higher spatial frequency components are quantized in sequence.
2. An image processing method according to claim 1 , further including:
coding, in sequence, data of the spatial frequency components quantized by said quantizing, and then storing the thus coded data in a memory.
3. An image processing method according to claim 2 , further including:
reading out the coded data stored in the memory starting from lower frequency spatial frequency components thereof after completing said converting, said quantizing and said coding, and then generating coded image data.
4. An image processing method according to claim 3 , wherein the coded image data are image data complying with a JPEG2000 format.
5. An image processing method according to claim 4 , wherein the conversion processing is a wavelet transform.
6. An image processing method according to claim 2 , wherein the conversion processing is a wavelet transform.
7. An image processing method according to claim 3 , wherein the conversion processing is a wavelet transform.
8. An image processing method according to claim 1 , wherein the conversion processing is a wavelet transform.
9. An image coding apparatus, comprising:
a conversion unit which converts an image into spatial frequency components; and
a quantizer which quantizes the spatial frequency components obtained by said conversion unit,
wherein said conversion unit performs a conversion processing that is of a form such that low frequency components of the image are obtained after high frequency components of the image are obtained, and
wherein said quantizer quantizes, in sequence, the spatial frequency components outputted from said conversion unit, without waiting for the completion of a processing by said conversion unit.
10. An image coding apparatus according to claim 9 , further comprising:
a coder which codes, in sequence, data of the spatial frequency components quantized by said quantizer; and
a coded data storage which temporarily stores the coded data generated by said coder, in order to rearrange the coded data in a predetermined sequence.
11. An image coding apparatus according to claim 10 , further comprising:
a stream generator which reads out, in the predetermined sequence, the coded data stored in said coded data storage and generates coded image data.
12. An image coding apparatus according to claim 11 , wherein said stream generator generates coded image data having a data structure such that lower frequency components appear first.
13. An image coding apparatus according to claim 12 , wherein the coded image data are image data complying with a JPEG2000 format.
14. An image coding apparatus according to claim 13 , wherein said conversion unit performs a wavelet transform.
15. An image coding apparatus according to claim 9 , wherein said conversion unit performs a wavelet transform.
16. An image coding apparatus according to claim 10 , wherein said conversion unit performs a wavelet transform.
17. An image coding apparatus according to claim 11 , wherein the coded image data are image data complying with a JPEG2000 format.
18. An image coding apparatus according to claim 17 , wherein said conversion unit performs a wavelet transform.
19. An image coding apparatus according to claim 11 , wherein said conversion unit performs a wavelet transform.
20. An image coding apparatus according to claim 12 , wherein said conversion unit performs a wavelet transform.