Python image processing combat reading notes

While reading the book "Image Processing, Analysis and Machine Vision", I use the book "Python Image Processing Practice" as a code-assisted reference book.During the reading process, I found that some codes in "Python Image Processing Practice" had some mismatches in actual use, as well as some findings that I thought were useful, so I made some notes to help me remember.
The version of the book "Python Image Processing Practice" in my hand is: the first edition in December 2020, and the second printing in Hebei in January 2021.

1. Section 1.4.3 of the book, Section 2. Read and display multiple images at once (14 pages), my solution is as follows:

ic = imread_collection(ic = imread_collection(['images/69015.jpg','images/210088.jpg', 'images/cat1.png'])imshow_collection(ic)show()

2. In section 1.5.2 of the book, section 1. (page 21) uses slices of numpy arrays for image processing, the code applies a circular mask to the lena image, but in the actual code, the mask is addedWhen the object is in a read-only state, it cannot be modified successfully.An invalid solution is to set lena.flags.writable=True, which will report cannot set WRITEABLE flag to True of this array.A valid solution is to construct a new object based on the original lena object.lena = np.array(lena).
3. It is also section 1.5.2 (page 21). In practice, it is found that the ndarray image obtained after the .png image is read in is of type float, and the .jpg image is of type uint8 after being read in. Its internal mechanismThe principles will be experienced in the future learning process.