README.md

@@ -77,14 +77,6 @@ Bugs
    files with other colorspaces, you must explicitly specify it using the
    `--colorspace` option.
 
- - Input images with alpha channels are not allowed. PDF only supports
-   transparency using binary masks but is unable to store 8-bit transparency
-   information as part of the image itself. But img2pdf will always be lossless
-   and thus, input images must not carry transparency information. You can
-   remove the alpha channel for example with imagemagick:
-
-    convert input.png -background white -alpha remove -alpha off output.png
-
  - An error is produced if the input image is broken. This commonly happens if
    the input image has an invalid EXIF Orientation value of zero. Even though
    only nine different values from 1 to 9 are permitted, Anroid phones and

src/img2pdf.py

@@ -3355,9 +3355,9 @@ Losslessly convert raster images to PDF without re-encoding PNG, JPEG, and
 JPEG2000 images. This leads to a lossless conversion of PNG, JPEG and JPEG2000
 images with the only added file size coming from the PDF container itself.
 Other raster graphics formats are losslessly stored using the same encoding
-that PNG uses. Since PDF does not support images with transparency and since
-img2pdf aims to never be lossy, input images with an alpha channel are not
-supported.
+that PNG uses.
+For images with transparency, the alpha channel will be stored as a separate
+soft mask. This is lossless, too.
 
 The output is sent to standard output so that it can be redirected into a file
 or to another program as part of a shell pipe. To directly write the output