scanning under windows WIA with custom settings (dpi / etc ) [Python]

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From: News123 on 22 Nov 2009 12:32

Hi,

I'm trying to scan a document from a python 2.6 script without user
interaction.

I found a code snippet, that allows me to scan under Vista, but that
doesn't allow me to select the dpi / color mode / etc.

The snippet uses win32com.client

# ##################### script start
import win32com.client,os

WIA_IMG_FORMAT_PNG = "{B96B3CAF-0728-11D3-9D7B-0000F81EF32E}"
WIA_COMMAND_TAKE_PICTURE = "{AF933CAC-ACAD-11D2-A093-00C04F72DC3C}"

os.chdir('c:/temp')
wia = win32com.client.Dispatch("WIA.CommonDialog")
dev = wia.ShowSelectDevice()
for command in dev.Commands:
if command.CommandID==WIA_COMMAND_TAKE_PICTURE:
foo=dev.ExecuteCommand(WIA_COMMAND_TAKE_PICTURE)
i=1
for item in dev.Items:
if i==dev.Items.Count:
image=item.Transfer(WIA_IMG_FORMAT_PNG)
break
i=i+1

image.SaveFile("test.png")
######################### script end

My problems are:

- This script works fine for me under Windows 7, however I'm
unable to specify additional parameters, like dpi and
color mode.

- The script doesn't work under windows XP, though the scanner driver is
installed. (Gimp finds the scanner (as WIA scanner)).
Perhaps 'WIA.CommonDialig' has another name or I need to install some DLL.
The error message is:
--------------------------------------------------------------------
Traceback (most recent call last):
File "C:\work\python\minidemos\wia_get_simple.py", line 7, in <module>
wia = win32com.client.Dispatch("WIA.CommonDialog")
File "C:\Python26\lib\site-packages\win32com\client\__init__.py", line
95, in Dispatch
dispatch, userName =
dynamic._GetGoodDispatchAndUserName(dispatch,userName,clsctx)
File "C:\Python26\lib\site-packages\win32com\client\dynamic.py", line
104, in _GetGoodDispatchAndUserName
return (_GetGoodDispatch(IDispatch, clsctx), userName)
File "C:\Python26\lib\site-packages\win32com\client\dynamic.py", line
84, in _GetGoodDispatch
IDispatch = pythoncom.CoCreateInstance(IDispatch, None, clsctx,
pythoncom.IID_IDispatch)
com_error: (-2147221005, 'Invalid class string', None, None)
---------------------------------------------------------------------

As I have no knowledge of Win32com and WIA I would appreciate some help
or good documentation about wincom32 / WIA with python

thanks for your help and bye

N

From: r on 23 Nov 2009 02:18

On Nov 22, 11:32 am, News123 <news...(a)free.fr> wrote:

> - This script works fine for me under Windows 7, however I'm
> unable to specify additional parameters, like dpi and
> color mode.

I have found something interesting but have no idea HOW to implement
it?? It seems the setting for the scanner are in the registry and must
be changed that way or by specifically calling these constants on the
device.

WIA_IPS_YRES (ScannerPictureYres)
Contains the current vertical resolution, in pixels per inch, for the
device. An application sets this property to set the vertical
resolution. The minidriver creates and maintains this property. Type:
VT_I4, Access: Read/Write or Read Only, Valid Values: WIA_PROP_RANGE
or WIA_PROP_LIST

WIA_IPS_XRES (ScannerPictureXres)
Contains the current horizontal resolution, in pixels per inch, for
the device. An application sets this property to set the horizontal
resolution. The minidriver creates and maintains this property. Type:
VT_I4, Access: Read/Write or Read Only, Valid Values: WIA_PROP_RANGE
or WIA_PROP_LIST

WIA_IPS_OPTICAL_XRES (ScannerPictureOpticalXres)
Note This property is supported only by Windows Vista and later.
Horizontal Optical Resolution. Highest supported horizontal optical
resolution in DPI. This property is a single value. This is not a list
of all resolutions that can be generated by the device. Rather, this
is the resolution of the device's optics. The minidriver creates and
maintains this property. This property is required for all items.
Type: VT_I4, Access: Read Only, Valid values: WIA_PROP_NONE

WIA_IPS_OPTICAL_YRES (ScannerPictureOpticalYres)
Note This property is supported only by Windows Vista and later.
Vertical Optical Resolution. Highest supported vertical optical
resolution in DPI. This property is a single value. This is not a list
of all resolutions that are generated by the device. Rather, this is
the resolution of the device's optics. The minidriver creates and
maintains this property. This property is required for all items.Type:
VT_I4, Access: Read Only, Valid values: WIA_PROP_NONE

WIA_IPS_BRIGHTNESS (ScannerPictureBrightness)
The image brightness values available within the scanner.Contains the
current hardware brightness setting for the device. An application
sets this property to the hardware's brightness value. The minidriver
creates and maintains this property. Type: VT_I4, Access: Read/Write,
Valid Values: WIA_PROP_RANGE

WIA_IPS_CONTRAST (ScannerPictureContrast)
Contains the current hardware contrast setting for a device. An
application sets this property to the hardware's contrast value. The
minidriver creates and maintains this property. Type: VT_I4, Access:
Read/Write, Valid Values: WIA_PROP_RANGE

WIA_IPS_ORIENTATION (ScannerPictureOrientation)
Specifies the current orientation of the documents to be scanned. The
minidriver creates and maintains this property. Type: VT_I4, Access:
Read/Write, Valid Values: WIA_PROP_LIST

------------------------
Image Intent Constants
------------------------
Image intent constants specify what type of data the image is meant to
represent. The WIA_IPS_CUR_INTENT scanner property uses these flags.
To provide an intent, combine an intended image type flag with an
intended size/quality flag by using the OR operator. WIA_INTENT_NONE
should not be combined with any other flags. Note that an image cannot
be both grayscale and color.

WIA_INTENT_IMAGE_TYPE_COLOR (ImageTypeColor)
WIA_INTENT_IMAGE_TYPE_GRAYSCALE (ImageTypeGrayscale)
WIA_INTENT_IMAGE_TYPE_TEXT (ImageTypeText)
WIA_INTENT_MINIMIZE_SIZE (MinimizeSize)
WIA_INTENT_MAXIMIZE_QUALITY (MaximizeQuality)
WIA_INTENT_BEST_PREVIEW (BestPreview)

From: News123 on 23 Nov 2009 03:30

Hi r,

r wrote:
> On Nov 22, 11:32 am, News123 <news...(a)free.fr> wrote:
>
>> - This script works fine for me under Windows 7, however I'm
>> unable to specify additional parameters, like dpi and
>> color mode.
>
> I have found something interesting but have no idea HOW to implement
> it?? It seems the setting for the scanner are in the registry and must
> be changed that way or by specifically calling these constants on the
> device.
>
> WIA_IPS_YRES (ScannerPictureYres)
> Contains the current vertical resolution, in pixels per inch, for the
> device. An application sets this property to set the vertical
> resolution. The minidriver creates and maintains this property. Type:
> VT_I4, Access: Read/Write or Read Only, Valid Values: WIA_PROP_RANGE
> or WIA_PROP_LIST
>

This sounds interesting.

I do have two questions:

1.) do these entries really have an impact?
---------------------------------------------
Did you find out whether changing the resolution or color mode in the
registry has really an impact when scanning an image with my python script?

2.) Where are these registry entries?
---------------------------------------

Under which windows version did you find these registry entries (XP,
Vista or Win7)?

I can't locate them, but probably my approach is too naive.
I started regedit and searched with CTRL-F for 'WIA_IPS_YRES'.

Perhaps these settings are scanner dependant?

My current script:
# ##################### script start
import win32com.client,os

WIA_IMG_FORMAT_PNG = "{B96B3CAF-0728-11D3-9D7B-0000F81EF32E}"
WIA_COMMAND_TAKE_PICTURE = "{AF933CAC-ACAD-11D2-A093-00C04F72DC3C}"

os.chdir('c:/temp')
wia = win32com.client.Dispatch("WIA.CommonDialog")
dev = wia.ShowSelectDevice()
for command in dev.Commands:
if command.CommandID==WIA_COMMAND_TAKE_PICTURE:
foo=dev.ExecuteCommand(WIA_COMMAND_TAKE_PICTURE)
i=1
for item in dev.Items:
if i==dev.Items.Count:
image=item.Transfer(WIA_IMG_FORMAT_PNG)
break
i=i+1

image.SaveFile("test.png")
######################### script end

bye

N

From: News123 on 23 Nov 2009 03:31

From: r on 23 Nov 2009 03:59

more *maybe useful dump?

>>> for i in dev.Items:
for p in i.Properties:
if not p.IsReadOnly:
print p.Name, '->', p.Value

Color Profile Name -> sRGB Color Space Profile
Brightness -> 0
Contrast -> 0
Private Highlight Level -> 0
Private Midtone Level -> 0
Private Shadow Level -> 0
Private Gamma -> 2200
Private Saturation -> 1000
Private Hue X -> 0
Private Hue Y -> 0
Private Sharpen Level -> 3
Threshold -> 55
Horizontal Resolution -> 200
Vertical Resolution -> 200
Horizontal Start Position -> 0
Vertical Start Position -> 0
Horizontal Extent -> 1700
Vertical Extent -> 2338
Current Intent -> 0
Data Type -> 3
Media Type -> 128
Format -> {B96B3CAA-0728-11D3-9D7B-0000F81EF32E}
Private Source Depth -> 0
Private Preview -> 0
Private Exposure Method -> 0
Private Smoothing -> 1
Private Color Enhanced -> 0
Private TMA Method -> 0

>>> dev.DeviceID
u'{6BDD1FC6-810F-11D0-BEC7-08002BE2092F}\\0000'

>>> for p in dev.Properties:
print p.Name, '->', p.Value

Item Name -> Root
Full Item Name -> 0000\Root
Item Flags -> 76
Unique Device ID -> {6BDD1FC6-810F-11D0-BEC7-08002BE2092F}\0000
Manufacturer -> Hewlett-Packard
Description -> HP Deskjet F300
Type -> 65538
Port -> \\.\Usbscan0
Name -> HP Deskjet F300
Server -> local
Remote Device ID ->
UI Class ID -> {0A8DC120-D685-4247-9CD1-8712F6BB2DED}
Hardware Configuration -> 0
BaudRate ->
STI Generic Capabilities -> 48
WIA Version -> 2.0
Driver Version -> 0.0.0.216
PnP ID String -> \\?\usb#vid_03f0&pid_5511&mi_00#6&2def7e7&0&0000#
{6bdd1fc6-810f-11d0-bec7-08002be2092f}
STI Driver Version -> 2
Horizontal Bed Size -> 8500
Vertical Bed Size -> 11690
Horizontal Bed Registration -> 0
Vertical Bed Registration -> 0
Access Rights -> 3
Horizontal Optical Resolution -> 2400
Vertical Optical Resolution -> 2400
Firmware Version -> 1.0.na
Max Scan Time -> 500000

Now how to set the values... hmmm?

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