Get bounding box of an image using xref

[mohammadmjn]

Is there any approach to get image bbox using xref or any other methods which are faster than page.get_image_bbox(image)? I used page.get_image_bbox(image) but it's slow for my use case where I have a vector PDF with a lot of small raster images (with more than 500 raster images). I have to detect the image bbox to check the size of each image with the page size to decide the whole page is a raster or vector. I also checked the xref but it gives me the actual image size that in most cases the image width and height we get from xref of the object is larger than its size in PDF (its width and height obtained from bbox). Here in my current code in which I want to replace page.get_image_bbox(image) with a solution based on xref or other faster alternatives to page.get_image_bbox:

def find_images_bbox(file_path):
    doc = fitz.open(path)
    page = doc[0]
    image_list = doc.get_page_images(0, full=True)
    for i in range(len(image_list)):
        image_bbox = page.get_image_bbox(image_list[i])
        print('image {} Bbox: {}'.format(i, image_bbox))
    doc.close()

[JorjMcKie]

You don't seem to need the xref at all, do you? Or any detail on how the page appearance references the image?
If I get you right, all you need are bbox coordinates of raster images actually shown on the page.

If this is true, I recommend you use text extraction - although this seems not to be obvious:
There is a performance oriented variant, which delivers text blocks of which every image is represented by a line of text with image metadata:

pprint([b for b in page.get_text("blocks") if b[-1] == 1])  # take only image blocks
[(344.25,
  88.93597412109375,
  540.0,
  175.18597412109375,
  '<image: DeviceRGB, width 261, height 115, bpc 8>',
  0,
  1)]

An image block is represented by a 1 as last item. The first 4 items of each block represent the bbox of the text block, in our case the bbox of the image.
Here is a runtime comparison for a page with 218 images:

In [8]: %timeit imgs=[b for b in page.get_text("blocks") if b[-1] == 1]
22.4 ms ± 245 µs per loop (mean ± std. dev. of 7 runs, 10 loops each)
In [9]: images = doc.get_page_images(1,full=True)
In [10]: %timeit  imgs=[page.get_image_bbox(i) for i in images]
2.46 s ± 10.7 ms per loop (mean ± std. dev. of 7 runs, 1 loop each)
In [11]:

So you have 22.4 milliseconds versus 2.46 seconds.
Is that fast enough for you?

[JorjMcKie]

The reason why we have such an apparent functional overlap here is, that the text extraction works for all document types - not just PDFs.
So, from looking at extracted text of whatever output variant, a reference back to any PDF definition specifics is not possible.

The doc.get_page_images() method and friends are for PDF only. Mehod page.get_image_bbox() also is for PDF only. I built it for cases where a reference between the page object definition and the page appearance definition is needed.