Mismatch between images displayed and named in /Resources

[frischzenger]

Please provide all mandatory information!

Describe the bug (mandatory)

When extract image from current page, it will returns all page's images

To Reproduce (mandatory)

def extract_image():
doc = fitz.open("xxxxxxx.pdf") # open a document

for page_index in range(len(doc)): # iterate over pdf pages
    page = doc[page_index] # get the page
    image_list = page.get_images()
	
    # print the number of images found on the page
    if image_list:
        print(f"Found {len(image_list)} images on page {page_index}")
    else:
        print("No images found on page", page_index)
        
    for image_index, img in enumerate(image_list, start=1): # enumerate the image list
        xref = img[0] # get the XREF of the image
        pix = fitz.Pixmap(doc, xref) # create a Pixmap

        if pix.n - pix.alpha > 3: # CMYK: convert to RGB first
            pix = fitz.Pixmap(fitz.csRGB, pix)

        pix.save(".\\tmp\\page_%s-image_%s.png" % (page_index, image_index)) # save the image as png
        pix = None

Expected behavior (optional)

When extract image from current page, it will returns current page's images

Screenshots (optional)

Your configuration (mandatory)

• Window11 home edition
• Anaconda3 python3.10
• PyMuPDF version('1.23.5', '1.23.4', '20231011000001')

Additional context (optional)

[julian-smith-artifex-com]

Do you have an example PDF that shows this problem?

[frischzenger]

Do you have an example PDF that shows this problem?

https://www.goodix.com/zh/docview/GProgrammer%E7%94%A8%E6%88%B7%E6%89%8B%E5%86%8C?objectId=108&objectType=document&version=503

[JorjMcKie]

This is not a bug:
The page's /Resources object names all these images, although the page itself does not display them. in PDF it is possible to do that.
It was the decision of the PDF creator to do so - whatever the motives.
If you want to change that, you can execute page.clean_contents() and save the PDF again using garbage option 2 or higher.
If you want to know which images the page page actually displays, use page.get_image_info()`.

[frischzenger]

This is not a bug: The page's /Resources object names all these images, although the page itself does not display them. in PDF it is possible to do that. It was the decision of the PDF creator to do so - whatever the motives. If you want to change that, you can execute page.clean_contents() and save the PDF again using garbage option 2 or higher. If you want to know which images the page page actually displays, use page.get_image_info()`.

when I use page.get_image_info(), and I get:

[{'number': 1, 'bbox': (148.01400756835938, 53.072998046875, 463.9859924316406, 279.843994140625), 'transform': (315.97198486328125, 0.0, -0.0, 226.77099609375, 148.01400756835938, 53.072998046875), 'width': 503, 'height': 361, 'colorspace': 1, 'cs-name': 'Indexed(255,DeviceRGB)', 'xres': 96, 'yres': 96, 'bpc': 8, 'size': 65723}, {'number': 6, 'bbox': (148.01400756835938, 397.43402099609375, 463.9859924316406, 624.2050170898438), 'transform': (315.97198486328125, 0.0, -0.0, 226.77099609375, 148.01400756835938, 397.43402099609375), 'width': 503, 'height': 361, 'colorspace': 1, 'cs-name': 'Indexed(255,DeviceRGB)', 'xres': 96, 'yres': 96, 'bpc': 8, 'size': 64160}]

page = doc[page_index] # get the page
image_list = page.get_images()
#which image is :
im_idx = page.get_image_info()[0]['number']
image_list[im_idx ]

and I show the image by the field 'number', but it's not correspondes to the image of that page displayed

[JorjMcKie]

As the documentation says:
There is no reliable relationship between images referenced in page.get_images() and the images actually displayed.
You can have 500 images listed in page.get_images() and the page shows no image at all.
And the reverse is also possible: the page may display an image which is not in that other list.

[JorjMcKie]

In addition, an image occuring with some number in page.get_image_info() does not mean that image is shown as the first on the page.
That number only means the sequence number of the display command. The image itself may still be shown at the bottom of the page.