Image processing apparatus, image processing method, non-transitory computer-readable storage medium storing program
An image processing apparatus with a processor and a memory storing instructions, that, when executed, cause the processor to obtain HDR data representing a high-dynamic range (HDR) image, in an image transfer function of the HDR data, a tone of each pixel is defined based on a relative luminance value, to obtain print information to perform printing based on the obtained HDR data, to set luminance information to be a target absolute luminance value, and to perform a luminance conversion on the HDR data so that a tone of each pixel is defined based on an absolute luminance value and the target absolute luminance value being a maximum luminance, to convert a dynamic range of luminance of the HDR data, on which the luminance conversion has been performed, into a dynamic range corresponding to printing of an image on a print medium performed based on the print information.
1. An image processing apparatus comprising:
at least one processor having a memory storing instructions, that when executed by the processor, cause the processor at least:
to obtain high-dynamic range (HDR) data that represents a high-dynamic range (HDR) image, wherein a tone of each pixel of the HDR image is defined based on a relative luminance value that has no units and whose physical quantity is not identifiable by the relative luminance value alone, and a dynamic range of luminance of the HDR data is not defined based on an absolute luminance value that has a unit and whose physical quantity is identifiable by the unit alone;
to obtain print information to perform printing based on the obtained HDR data;
to set luminance information for defining the dynamic range of luminance of the HDR data based on the absolute luminance value by converting the relative luminance value of the obtained HDR data into the absolute luminance value;
to perform, based on the set luminance information, a first conversion for defining the dynamic range of luminance of the HDR data by converting the relative luminance value of the obtained HDR data into the absolute luminance value; and
to perform a second conversion for converting a dynamic range of luminance of the HDR data, on which the first conversion has been performed, into a dynamic range corresponding to printing of an image on a print medium to be performed as specified by the obtained print information.
2. The apparatus according to claim 1 , wherein the print information is information for specifying a dynamic range to be obtained by the second conversion.
3. The apparatus according to claim 2 , wherein the print information includes information that indicates a type of a sheet to be printed.
4. The apparatus according to claim 1 , wherein the obtained HDR data is data after optoelectronic conversion on an image capturing side.
5. The apparatus according to claim 1 , wherein the at least one processor is further caused to display the luminance information of a display apparatus, wherein the luminance information of the display apparatus is set.
6. The apparatus according to claim 5 , wherein, in a case in which the luminance information of a plurality of display apparatuses is obtained, the luminance information corresponding to the plurality of display apparatuses is set.
7. The apparatus according to claim 1 , wherein the at least one processor is further caused to hold the absolute luminance value.
8. The apparatus according to claim 1 , wherein the at least one processor is further caused to perform the second conversion by using conversion information for converting a dynamic range.
9. The apparatus according to claim 1 , wherein the at least one processor is further caused to convert the dynamic range of the luminance of the HDR data on which the first conversion has been performed, into a dynamic range, corresponding to printing to be performed, so that input luminance and output luminance will match within a predetermined luminance range by performing a linear conversion from a dark portion to a specific luminance portion, and performing a conversion by a logarithmic characteristic in a highlight portion.
10. The apparatus according to claim 1 , wherein the at least one processor is further caused to divide an image represented by the HDR data into regions, and
wherein the second conversion is performed by using conversion information that is used to convert a dynamic range and is set for each divided region.
11. The apparatus according to claim 10 , wherein region division is performed on a low-frequency component of the image represented by the HDR data.
12. The apparatus according to claim 11 , wherein the at least one processor is further caused to perform contrast correction on a high-frequency component of the image represented by the HDR data.
13. The apparatus according to claim 1 , wherein the at least one processor is further caused to perform printing based on data that has undergone the second conversion.
14. The apparatus according to claim 1 , wherein the HDR data is data defined by a Hybrid Log Gamma (HLG) method.
15. The apparatus according to claim 1 , wherein the at least one processor is further caused:
to obtain luminance dynamic range information of each of a plurality of display apparatuses; and
to set the luminance dynamic range information of a display apparatus with the narrowest luminance dynamic range among the plurality of display apparatuses as the luminance information for defining the dynamic range of luminance of the HDR data based on the absolute luminance value by converting the relative luminance value of the obtained HDR data into the absolute luminance value.
16. The apparatus according to claim 15 , wherein the at least one processor is further caused to obtain a maximum luminance value and a minimum luminance value that are luminance dynamic range information of each of a plurality of display apparatuses.
17. The apparatus according to claim 1 , wherein the at least one processor is further caused to obtain the luminance information for defining the dynamic range of luminance of the HDR data from a metadata portion of the HDR data.
18. The apparatus according to claim 17 , wherein the luminance information for defining the dynamic range of luminance of the HDR data is overwritten on the metadata portion of the HDR data after printing.
19. The apparatus according to claim 1 , wherein the at least one processor is further caused to perform, based on the set luminance information, the first conversion by using a transfer function.
20. The apparatus according to claim 19 , wherein the at least one processor is further caused to perform, based on the set luminance information, the first conversion by using an electro-optical transfer function and an opto-optical transfer function.
21. An image processing method to be executed in an image processing apparatus, the method comprising:
obtaining high-dynamic range (HDR) data that represents a high-dynamic range (HDR) image, wherein a tone of each pixel of the HDR image is defined based on a relative luminance value that has no units and whose physical quantity is not identifiable by the relative luminance value alone, and a dynamic range of luminance of the HDR data is not defined based on an absolute luminance value that has a unit and whose physical quantity is identifiable by the unit alone;
obtaining print information to perform printing based on the obtained HDR data;
setting luminance information for defining the dynamic range of luminance of the HDR data based on the absolute luminance value by converting the relative luminance value of the obtained HDR data into the absolute luminance value;
performing, based on the set luminance information, a first conversion for defining the dynamic range of luminance of the HDR data by converting the relative luminance value of the obtained HDR data into the absolute luminance value; and
performing a second conversion for converting a dynamic range of luminance of the HDR data, on which the first conversion has been performed, into a dynamic range corresponding to printing of an image on a print medium to be performed as specified by the obtained print information.
22. The method according to claim 21 , wherein the HDR data is data defined by a Hybrid Log Gamma (HLG) method.
23. A non-transitory computer-readable storage medium storing a program to cause a computer to function:
to obtain high-dynamic range (HDR) data that represents a high-dynamic range (HDR) image, wherein a tone of each pixel of the HDR image is defined based on a relative luminance value that has no units and whose physical quantity is not identifiable by the relative luminance value alone, and a dynamic range of luminance of the HDR data is not defined based on an absolute luminance value that has a unit and whose physical quantity is identifiable by the unit alone;
to obtain print information to perform printing based on the obtained HDR data;
to set luminance information for defining the dynamic range of luminance of the HDR data based on the absolute luminance value by converting the relative luminance value of the obtained HDR data into the absolute luminance value;
to perform, based on the set luminance information, a first conversion for defining the dynamic range of luminance of the HDR data by converting the relative luminance value of the obtained HDR data into the absolute luminance value; and
to perform a second conversion for converting a dynamic range of luminance of the HDR data, on which the first conversion has been performed, into a dynamic range corresponding to printing of an image on a print medium to be performed as specified by the obtained print information.
24. The medium according to claim 23 , wherein the HDR data is data defined by a Hybrid Log Gamma (HLG) method.