edcc7ea34f
* add __all__ to files "adjustmentsinfo.py" and "albuminfo.py" * add __all__ to file "cli.py" * add __all__ to all files that misses except files with prefix "_"
128 lines
4.9 KiB
Python
128 lines
4.9 KiB
Python
""" ImageConverter class
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Convert an image to JPEG using CoreImage --
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for example, RAW to JPEG. Only works if Mac equipped with GPU. """
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# reference: https://stackoverflow.com/questions/59330149/coreimage-ciimage-write-jpg-is-shifting-colors-macos/59334308#59334308
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import pathlib
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import objc
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import Metal
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import Quartz
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from Cocoa import NSURL
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from Foundation import NSDictionary
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# needed to capture system-level stderr
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from wurlitzer import pipes
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__all__ = ["ImageConversionError", "ImageConverter"]
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class ImageConversionError(Exception):
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"""Base class for exceptions in this module."""
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pass
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class ImageConverter:
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"""Convert images to jpeg. This class is a singleton
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which will re-use the Core Image CIContext to avoid
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creating a new context for every conversion."""
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def __new__(cls, *args, **kwargs):
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"""create new object or return instance of already created singleton"""
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if not hasattr(cls, "instance") or not cls.instance:
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cls.instance = super().__new__(cls)
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return cls.instance
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def __init__(self):
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"""return existing singleton or create a new one"""
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if hasattr(self, "context"):
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return
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""" initialize CIContext """
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context_options = NSDictionary.dictionaryWithDictionary_(
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{
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"workingColorSpace": Quartz.CoreGraphics.kCGColorSpaceExtendedSRGB,
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"workingFormat": Quartz.kCIFormatRGBAh,
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}
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)
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self.context = Quartz.CIContext.contextWithOptions_(context_options)
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def write_jpeg(self, input_path, output_path, compression_quality=1.0):
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"""convert image to jpeg and write image to output_path
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Args:
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input_path: path to input image (e.g. '/path/to/import/file.CR2') as str or pathlib.Path
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output_path: path to exported jpeg (e.g. '/path/to/export/file.jpeg') as str or pathlib.Path
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compression_quality: JPEG compression quality, float in range 0.0 to 1.0; default is 1.0 (best quality)
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Return:
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True if conversion successful, else False
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Raises:
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ValueError if compression quality not in range 0.0 to 1.0
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FileNotFoundError if input_path doesn't exist
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ImageConversionError if error during conversion
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"""
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# Set up a dedicated objc autorelease pool for this function call.
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# This is to ensure that all the NSObjects are cleaned up after each
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# call to prevent memory leaks.
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# https://developer.apple.com/library/archive/documentation/Cocoa/Conceptual/MemoryMgmt/Articles/mmAutoreleasePools.html
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# https://pyobjc.readthedocs.io/en/latest/api/module-objc.html#memory-management
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with objc.autorelease_pool():
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# accept input_path or output_path as pathlib.Path
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if not isinstance(input_path, str):
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input_path = str(input_path)
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if not isinstance(output_path, str):
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output_path = str(output_path)
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if not pathlib.Path(input_path).is_file():
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raise FileNotFoundError(f"could not find {input_path}")
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if not (0.0 <= compression_quality <= 1.0):
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raise ValueError(
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"illegal value for compression_quality: {compression_quality}"
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)
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input_url = NSURL.fileURLWithPath_(input_path)
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output_url = NSURL.fileURLWithPath_(output_path)
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with pipes() as (out, err):
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# capture stdout and stderr from system calls
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# otherwise, Quartz.CIImage.imageWithContentsOfURL_
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# prints to stderr something like:
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# 2020-09-20 20:55:25.538 python[73042:5650492] Creating client/daemon connection: B8FE995E-3F27-47F4-9FA8-559C615FD774
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# 2020-09-20 20:55:25.652 python[73042:5650492] Got the query meta data reply for: com.apple.MobileAsset.RawCamera.Camera, response: 0
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input_image = Quartz.CIImage.imageWithContentsOfURL_(input_url)
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if input_image is None:
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raise ImageConversionError(f"Could not create CIImage for {input_path}")
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output_colorspace = (
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input_image.colorSpace()
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or Quartz.CGColorSpaceCreateWithName(
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Quartz.CoreGraphics.kCGColorSpaceSRGB
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)
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)
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output_options = NSDictionary.dictionaryWithDictionary_(
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{"kCGImageDestinationLossyCompressionQuality": compression_quality}
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)
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(
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_,
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error,
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) = self.context.writeJPEGRepresentationOfImage_toURL_colorSpace_options_error_(
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input_image, output_url, output_colorspace, output_options, None
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)
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if not error:
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return True
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else:
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raise ImageConversionError(
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f"Error converting file {input_path} to jpeg at {output_path}: {error}"
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)
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