The PIL handbook, modern equivalents

Snapshots of the original handbook are in the Internet Archive. It remains a good explanation of the model, as long as you translate the Python 2 syntax and the constants that have since moved.

The modules

Module	What it does	Here
`Image`	Opening, saving, converting, resizing, the class everything returns	Image module
`ImageDraw`	Lines, shapes and text onto an image	ImageDraw
`ImageFilter`	Blur, sharpen, edge finding, custom kernels	ImageFilter
`ImageEnhance`	Brightness, contrast, colour, sharpness	ImageEnhance
`ImageOps`	Autocontrast, fit, pad, invert, exif_transpose	ImageOps
`ImageChops`	Channel arithmetic, difference, offset	Pillow docs
`ImageColor`	Colour names and strings to values	Palette tool
`ImageFont`	Bitmap and TrueType fonts	See the note on text below
`ImageTk`	Showing images in Tkinter	Tkinter introduction
`ImagePath`	Compact coordinate lists for drawing	ImagePath
`ImageFile`	Decoding from a stream, truncated files	ImageFile
`ImageSequence`	Frames of an animation	Pillow docs
`ImageStat`	Sums, means and extrema of an image	Pillow docs
`ImageGrab`	Screen captures	Pillow docs

The one that catches everybody

Handbook era code measures text like this:

w, h = draw.textsize("hello", font=font)

textsize was removed in Pillow 10. The replacement returns a box rather than a size:

left, top, right, bottom = draw.textbbox((0, 0), "hello", font=font)
w = right - left
h = bottom - top

The converter flags this, along with everything else that changed.

Start here instead

Concepts, bands, modes, sizes and coordinates
A short tutorial, the same ground the handbook introduction covered
The filter gallery, every filter shown on one image
Format support, read, write and the catches
Mode conversions, shown side by side
The whole thing as a PDF, 16 pages
The Image module
The Pillow documentation, which is the maintained reference