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    Converting images to webp or jpeg2000 in Pythonista

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    • mikael
      mikael @Niklas last edited by

      @Niklas, iOS Safari supports webp since iOS 14, so conversion should be possible in a WebView via JavaScript. Relevant-looking js sample here.

      And Apple Shortcuts supports image conversion to JPEG2000, so you might be able to do everything there, or branch out to run just the conversion in Shortcuts.

      1 Reply Last reply Reply Quote 0
      • Niklas
        Niklas last edited by

        Thank you, @mikael, doing it in Shortcuts worked perfectly! πŸ™‚ Like you, I tested different ways of making it work in Pythonista, but gave up. If someone else needs it, the shortcuts is here:

        https://www.icloud.com/shortcuts/de01f3230990494b85129535fa855d5d

        You can pick images from Photos or Files and it converts them to jpeg2000. Then you can save them back to Photos or Files.

        Hopefully it will be possible to do this in Pythonista eventually. πŸ™‚

        cvp 1 Reply Last reply Reply Quote 0
        • cvp
          cvp @Niklas last edited by cvp

          @Niklas I think that it could be possible that
          In Pythonista

          • you ask/get the image
          • you save the file in Files (in an external folder)
          • you start a shortcut which
            In your shortcut
          • you get the file from Files
          • you convert to jpeg2000
          • you save in Files
          • you start Pythonista script
            In Pythonista
          • you get the converted file
          • ...

          Γ‰dit: sorry, if it was what you want to say by "Hopefully it will be possible to do this in Pythonista eventually."

          1 Reply Last reply Reply Quote 0
          • Niklas
            Niklas last edited by

            Thank you! I’m thinking of doing something like that, but more or less only do the .jp2 conversion in Shortcuts and everything else in Pythonista. πŸ™‚

            What I meant by the sentence you quoted, is that I hope Pythonista will get built-in support for webp and jpeg2000 conversions in the future. Since that is what Google recommends if you want high website rankings in their search results, I think Pythonista would be a good place to have it on iPad.

            1 Reply Last reply Reply Quote 0
            • JonB
              JonB last edited by

              I believe that CGCreateDestination supports writing to j2k.

              https://stackoverflow.com/questions/19749482/how-do-i-convert-uiimage-to-j2k-jpeg2000-in-ios

              1 Reply Last reply Reply Quote 0
              • Niklas
                Niklas last edited by

                I tried to read and follow what they did there, but it was above my knowledge level. Thanks anyway! πŸ™‚

                1 Reply Last reply Reply Quote 0
                • Niklas
                  Niklas last edited by

                  A related question:

                  If I get a jp2 image from Shortcuts via the clipboard, can I save it to Files in Pythonista? When I try to do it with image.save(image-to-save) I get an OSError: encoder jpeg2k not available, which I can understand. I think there should be a way to disregard the file type and save it the way it came, without making any changes other than the file name.

                  Is this possible?

                  cvp mikael 2 Replies Last reply Reply Quote 0
                  • cvp
                    cvp @Niklas last edited by cvp

                    @Niklas why are you passing the image file as an image ? In shortcuts, you could save it in Files.

                    Γ‰dit: what do you want to do with this image in Pythonista?

                    1 Reply Last reply Reply Quote 0
                    • mikael
                      mikael @Niklas last edited by

                      @Niklas, PIL images have the tobytes method that could possibly do the trick, but see the warning in doc.

                      Probably better to save in Files, as @cvp suggested, and just pass the path. Then you can handle it in Pythonista like any other binary file.

                      1 Reply Last reply Reply Quote 0
                      • Niklas
                        Niklas last edited by

                        @cvp, my intention was to do as much as possible in Pythonista, since I find Shortcuts so slow. Your question got me to think and I went with your suggestion instead. πŸ™‚ Also, I already had a shortcut that did most of what I wanted.

                        @mikael, thanks for suggesting tobytes. I will try to keep that in mind for another time. πŸ™‚

                        cvp 1 Reply Last reply Reply Quote 0
                        • cvp
                          cvp @Niklas last edited by cvp

                          @Niklas I've tried during some hours to convert @JonB 's idea into Pythonista, but without any success. Sorry

                          mikael 1 Reply Last reply Reply Quote 1
                          • mikael
                            mikael @cvp last edited by

                            @cvp, want to share the code for some joint debugging?

                            cvp 1 Reply Last reply Reply Quote 0
                            • cvp
                              cvp @mikael last edited by

                              @mikael I think it is far from my skills

                              '''
                              https://stackoverflow.com/questions/19749482/how-do-i-convert-uiimage-to-j2k-jpeg2000-in-ios
                              
                              #import <ImageIO/ImageIO.h> // or @import ImageIO if modules enabled
                              #import <MobileCoreServices/MobileCoreServices.h>
                              
                              // ...    
                              
                              // quality is 0-1 (0 = smallest file size, 1 = lossless quality)
                              + (NSData*) convertToJPEG2000:(UIImage*)image withQuality:(float)quality
                              {
                                  NSMutableData* d = [NSMutableData data];
                                  CGImageDestinationRef destinationRef = CGImageDestinationCreateWithData((__bridge CFMutableDataRef)d, kUTTypeJPEG2000, 1, NULL);
                                  CGImageDestinationSetProperties(destinationRef, NULL);
                                  CGImageDestinationAddImage(destinationRef, image.CGImage, (__bridge CFDictionaryRef)@{ (NSString*)kCGImageDestinationLossyCompressionQuality: @(quality) });
                              
                                  if (!CGImageDestinationFinalize(destinationRef))
                                  {
                                      d = nil;
                                  }
                                  CFRelease(destinationRef);
                              
                                  return d;
                              }
                              '''
                              from   objc_util import *
                              import time
                              import ui
                              
                              d = NSMutableData
                              
                              CGImageDestinationCreateWithData = c.CGImageDestinationCreateWithData
                              CGImageDestinationCreateWithData.restype = c_void_p
                              CGImageDestinationCreateWithData.argtypes = [c_void_p, c_void_p, c_void_p, c_void_p]
                              
                              kUTTypeJPEG2000 = 'public.jpeg-2000'	# UTI for a Jpeg2000
                              
                              imagedest = CGImageDestinationCreateWithData(d, kUTTypeJPEG2000, 1, None)
                              
                              CGImageDestinationSetProperties = c.CGImageDestinationSetProperties
                              CGImageDestinationSetProperties.restype = None
                              CGImageDestinationSetProperties.argtypes = [c_void_p, c_void_p]
                              CGImageDestinationSetProperties(d, None)
                              
                              img = ui.Image.named('test:Peppers').with_rendering_mode(ui.RENDERING_MODE_ORIGINAL).objc_instance
                              
                              CGImageDestinationAddImage = c.CGImageDestinationAddImage
                              CGImageDestinationAddImage.restype = None
                              CGImageDestinationAddImage.argtypes = [c_void_p, c_void_p, c_void_p]
                              CGImageDestinationAddImage(d, img, None)# {ns('kCGImageDestinationLossyCompressionQuality'):1})
                              time.sleep(3)
                              
                              CFRelease = c.CFRelease
                              CFRelease.restype = None
                              CFRelease.argtypes = [c_void_p]
                              CFRelease(d)
                              
                              mikael 1 Reply Last reply Reply Quote 0
                              • mikael
                                mikael @cvp last edited by

                                @cvp, yeah, it looked more challenging than usual. Would it matter if you objc_util.load_framework('ImageIO') or not?

                                cvp 1 Reply Last reply Reply Quote 0
                                • cvp
                                  cvp @mikael last edited by

                                  @mikael sincerely, I don't know, I have stopped to spend time with this test.

                                  1 Reply Last reply Reply Quote 0
                                  • JonB
                                    JonB last edited by JonB

                                    You were really close! CGDestnationXXX() takes imagedest as first param. ine of the signatures was wrong (needed a size_t), and the kUTType ought to be an nsstring.

                                    This seems to work!
                                    (edit: refactored into a convienent function)
                                    (edit again, fixed a typo, added quality)

                                    '''
                                    https://stackoverflow.com/questions/19749482/how-do-i-convert-uiimage-to-j2k-jpeg2000-in-ios
                                    
                                    #import <ImageIO/ImageIO.h> // or @import ImageIO if modules enabled
                                    #import <MobileCoreServices/MobileCoreServices.h>
                                    
                                    // ...    
                                    
                                    // quality is 0-1 (0 = smallest file size, 1 = lossless quality)
                                    + (NSData*) convertToJPEG2000:(UIImage*)image withQuality:(float)quality
                                    {
                                        NSMutableData* d = [NSMutableData data];
                                        CGImageDestinationRef destinationRef = CGImageDestinationCreateWithData((__bridge CFMutableDataRef)d, kUTTypeJPEG2000, 1, NULL);
                                        CGImageDestinationSetProperties(destinationRef, NULL);
                                        CGImageDestinationAddImage(destinationRef, image.CGImage, (__bridge CFDictionaryRef)@{ (NSString*)kCGImageDestinationLossyCompressionQuality: @(quality) });
                                    
                                        if (!CGImageDestinationFinalize(destinationRef))
                                        {
                                            d = nil;
                                        }
                                        CFRelease(destinationRef);
                                    
                                        return d;
                                    }
                                    '''
                                    from   objc_util import *
                                    import ctypes
                                    import time
                                    import ui
                                    load_framework('ImageIO')
                                    
                                    CGImageDestinationCreateWithData = c.CGImageDestinationCreateWithData
                                    CGImageDestinationCreateWithData.restype = c_void_p
                                    CGImageDestinationCreateWithData.argtypes = [c_void_p, c_void_p, ctypes.c_size_t, c_void_p]
                                    
                                    CGImageDestinationSetProperties = c.CGImageDestinationSetProperties
                                    CGImageDestinationSetProperties.restype = None
                                    CGImageDestinationSetProperties.argtypes = [c_void_p, c_void_p]
                                    
                                    CGImageDestinationAddImage = c.CGImageDestinationAddImage
                                    CGImageDestinationAddImage.restype = None
                                    CGImageDestinationAddImage.argtypes = [c_void_p, c_void_p, c_void_p]
                                    
                                    CGImageDestinationFinalize=c.CGImageDestinationFinalize
                                    CGImageDestinationFinalize.restype=ctypes.c_int
                                    CGImageDestinationFinalize.argtypes=[c_void_p]
                                    
                                    CFRelease = c.CFRelease
                                    CFRelease.restype = None
                                    CFRelease.argtypes = [c_void_p]
                                    
                                    kUTTypeJPEG2000 =  c_void_p.in_dll(c,'kUTTypeJPEG2000')    # UTI for a Jpeg2000
                                    kCGImageDestinationLossyCompressionQuality=c_void_p.in_dll(c,'kCGImageDestinationLossyCompressionQuality')
                                    
                                    '''def convert_image_to_jpeg2000(uiimg, out_filename, quality=1):
                                    	uiimage=ui.Image
                                    	out_filename=str
                                    	quality: 0=smallest, 1=lossless'''
                                    def convert_image_to_jpeg2000(uiimg, out_filename, quality=1):
                                    	d = NSMutableData.new()
                                    	imagedest = CGImageDestinationCreateWithData(d, kUTTypeJPEG2000, 1, None)
                                    
                                    	CGImageDestinationSetProperties(imagedest, None)
                                    
                                    	#img = ui.Image.named('test:Peppers').with_rendering_mode(ui.RENDERING_MODE_ORIGINAL).objc_instance
                                    
                                    	CGImageDestinationAddImage(imagedest, uiimg.objc_instance.CGImage(),ns({'kCGImageDestinationLossyCompressionQuality':quality}))
                                    
                                    	if not CGImageDestinationFinalize(imagedest):
                                    		raise Exception('Image Conversion Failed')
                                    	CFRelease(imagedest)
                                    
                                    	with open(out_filename,'wb') as f:
                                    		f.write(nsdata_to_bytes(d))
                                    
                                    if __name__=='__main__': 		
                                    	img=ui.Image.named('test:Lenna')
                                    	convert_image_to_jpeg2000(img, 'lenna.j2k',0)
                                    
                                    	import console
                                    	console.quicklook('lenna.j2k')
                                    	print('success!' )
                                    	
                                    
                                    cvp 1 Reply Last reply Reply Quote 0
                                    • cvp
                                      cvp @JonB last edited by

                                      @JonB You're really the champion. Where could go this forum without you?
                                      Thanks for everybody.
                                      Sincerely, I don't know why I have even tried.

                                      JonB 1 Reply Last reply Reply Quote 0
                                      • JonB
                                        JonB @cvp last edited by

                                        @cvp You did the heavy lifting . A minor update above adds the quality parameter (at quality=1, lenna is 445kB. at 0, it is 3kB...

                                        mikael 1 Reply Last reply Reply Quote 1
                                        • mikael
                                          mikael @JonB last edited by

                                          @JonB, cannot guess the UTI for WebP. Would require a recompile of Pythonista to get the symbol included?

                                          1 Reply Last reply Reply Quote 0
                                          • JonB
                                            JonB last edited by

                                            I read somewhere that webp is not supported on iOS. Or, possibly, that newer safari versions might support display of webp, but I doubt that writing webp has been implemented in CGDestinationCreate.

                                            Found this on GitHub:

                                            // kUTTypeWebP seems not defined in public UTI framework, Apple use the hardcode string, we define them :)
                                            #define kSDUTTypeWebP ((__bridge CFStringRef)@"org.webmproject.webp")
                                            

                                            So, you might try ns('org.webmproject.webp').

                                            but again no guarantee that iOS can write webp without libwebm or freeimage or some other library.

                                            mikael 1 Reply Last reply Reply Quote 0
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