$ hp-scan -r 200 -mcolor -dhpaio:/net/HP_LaserJet_Pro_MFP_M125rnw?ip=***

HP Linux Imaging and Printing System (ver. 3.17.10)
Scan Utility ver. 2.2

Copyright (c) 2001-15 HP Development Company, LP
This software comes with ABSOLUTELY NO WARRANTY.
This is free software, and you are welcome to distribute it
under certain conditions. See COPYING file for more details.

warning: No destinations specified. Adding 'file' destination by default.
Using device hpaio:/net/HP_LaserJet_Pro_MFP_M125rnw?ip=***
Opening connection to device...

Resolution: 200dpi
Mode: color
Compression: JPEG
Scan area (mm):
  Top left (x,y): (0.000000mm, 0.000000mm)
  Bottom right (x,y): (215.899994mm, 296.925995mm)
  Width: 215.899994mm
  Height: 296.925995mm
Destination(s): file
Output file: 
warning: File destination enabled with no output file specified.
Setting output format to JPEG for color/lineart mode.
warning: Defaulting to '/home/***/hpscan001.jpg'.

Warming up...
 

Scanning...
Reading data: [**************************************************************************] 100%  11.4 MB   
Read 11.4 MB from scanner.
Closing device.

Outputting to destination 'file':
Saving to file /home/***/hpscan001.jpg
error: Error saving file: cannot write mode RGBA as JPEG (I/O)






$ hp-scan -r 200 -spdf -mcolor -dhpaio:/net/HP_LaserJet_Pro_MFP_M125rnw?ip=***

HP Linux Imaging and Printing System (ver. 3.17.10)
Scan Utility ver. 2.2

Copyright (c) 2001-15 HP Development Company, LP
This software comes with ABSOLUTELY NO WARRANTY.
This is free software, and you are welcome to distribute it
under certain conditions. See COPYING file for more details.

Using device hpaio:/net/HP_LaserJet_Pro_MFP_M125rnw?ip=***
Opening connection to device...

Resolution: 200dpi
Mode: color
Compression: JPEG
Scan area (mm):
  Top left (x,y): (0.000000mm, 0.000000mm)
  Bottom right (x,y): (215.899994mm, 296.925995mm)
  Width: 215.899994mm
  Height: 296.925995mm
Destination(s): pdf

Warming up...
 

Scanning...
Reading data: [**************************************************************************] 100%  11.4 MB   
Read 11.4 MB from scanner.
Closing device.

Sending to destination 'pdf':
Traceback (most recent call last):
  File "/usr/bin/hp-scan", line 1135, in <module>
    c.drawInlineImage(im, (tlx/0.3528), (tly/0.3528), ((brx-tlx)/0.3528),((bry-tly)/0.3528))
  File "/usr/lib64/python2.7/site-packages/reportlab/pdfgen/canvas.py", line 826, in drawInlineImage
    img_obj = PDFImage(image, x,y, width, height)
  File "/usr/lib64/python2.7/site-packages/reportlab/pdfgen/pdfimages.py", line 40, in __init__
    self.getImageData()
  File "/usr/lib64/python2.7/site-packages/reportlab/pdfgen/pdfimages.py", line 165, in getImageData
    imagedata, imgwidth, imgheight = self.PIL_imagedata()
  File "/usr/lib64/python2.7/site-packages/reportlab/pdfgen/pdfimages.py", line 125, in PIL_imagedata
    raw = myimage.tostring()
  File "/usr/lib64/python2.7/site-packages/PIL/Image.py", line 738, in tostring
    raise NotImplementedError("tostring() has been removed. "
NotImplementedError: tostring() has been removed. Please call tobytes() instead.