The MontiVision Image Renderer filter is used to create single image files, taken from a video stream. It supports the following file formats: Bitmap (*.bmp), JPEG (*.jpg), TIFF (*.tif), TARGA (*.tga) and PNG (*.png) and provides two working modes. All incoming images from the video stream can be saved to a directory or, if the filter uses the trigger mode, an image file saved on each trigger event. The names of the output files can be defined using filename templates (see below how to use templates). It is possible to capture a region of the video frame instead of capturing the whole frame. Also, the output image may be resized before it is written to disc.

This MontiVision DirectShow Filter is used in combination with the MontiVision Smart Control in the ImageStream Sample Application.

File:	ImageRenderer.ax
CLSID:	CLSID_MVImageRenderer

Supported Interfaces

IMVImageCapture

Supported COM Events

The filter supports following events through the IMVFilterEvents interface. Look at the filter events page for more information.

Event	Value	Description
MV_ALGORITHM_START_EVENT	0	A filter starts processing a video frame or sample.
MV_ALGORITHM_END_EVENT	1	A filter finishes processing a video frame or sample.
MV_IMAGE_CAPTURE_START_EVENT	2	Image capture started.
MV_IMAGE_CAPTURE_END_EVENT	3	Image capture to disc or memory finished.

Supported I/O Pins

I/O Pin	Corresponding method	Discription
Filename [String]	IMVImageCapture::put_FixedFileName	Sets the file name for the next image to be captured, if the filter doesn't use templates to create the file names.
Trigger [Boolean]	IMVTrigger::Trigger	Starts the capture of a snapshot, depending on the trigger mode. Example: If the trigger mode is MV_TRIGGER_RISING_EDGE, a snapshot is taken after the the Control I/O pin changes its state from FALSE to TRUE.
Result [String]	IMVImageInfo::GetCurrentFileName	Outputs the path to last captured image file.

Attention:
I/O Pins are dominat, what means that they have a higher priority than the corresponding method of the filters interface!

MV Image Renderer Property Pages

MontiVision Image File Renderer DirectShow Filter Capture Property Page
MV Image Renderer filter property page

This property page displays the image data and the filename of the last captured image. The trigger button activates the grabber and sets it to capture the next processed frame. It uses the IMVTrigger and the IMVImageInfo interface.

MontiVision Image Renderer DirectShow Filter Format Property Page
MV Image Renderer output file property page

This property page is used to specify the name, path and format of the captured images. It uses the IMVImageCapture interface.

Use filename	If this radio button is selected, the files are named using the text of the edit box to the right of the button. The name is extended by a counter that is incremented for every captured image.
Use templates	If this radio button is selected, the files are named using the template file that is specified by the edit box to the right of the button. See below how templates are used to create filenames.
Output folder	Used to specify the filters output folder. The captured image files are written there.
File format	Used to specify the file format that is used to write the captured images to the output folder.

MontiVision Image File Renderer DirectShow Filter ROI Property Page
MV Image Renderer capture region property page

This property page provides region of interest functionality. It is possible to capture a region of the video frame and resize it to a desired output size before it is written to disc. It uses the IMVImageCapture2 interface.

Origin	Used to specify the horizontal and vertical offset to the ractangle that is to be captured.
Dimension	Used to specify the width and the height of the rectangle that is to be captured.
Output image dimension	The captured image may be resized before it is written to disc. Those settings specify the dimension of the resized image.
Interpolation	Interpolation used for resizing.

Template files

The filter uses template files to create the output files names. The template file is a simple text file using the following syntax:

Text	Output as it is.
Variable	%Variable Name%
%	%%

Template variables

The following table shows all fixed variables for template files.

YEAR	4 digit year, e.g. 2003.
SHORT_YEAR	2 digit year, e.g. 03
MONTH	2 digit month, e.g 01
MONTH_NAME	Name of the month, e.g. January.
DAY	2 ditit day, e.g 29.
DAY_NAME	Weekname of the day, e.g. Monday.
WEEK	2 digt week number, e.g. 45.
HOUR	2 digit hour, e.g. 17.
MINUTE	2 digit minute, e.g. 54.
SECOND	2 digit second, e.g. 32.
FILE_COUNT	Counter for the files created by the filter.

Examples:

1. Using templates to create output filenames

The output folder "C:\Images\" is specified, the JPEG format is selected and the specified template file "C:\Templates\output_filename.txt" is specifidied. This template file contains the following text:

%YEAR%-%MONTH%-%DAY%_File_%FILE_COUNT%

The resulting filenames of the captured image files are:

c:\images\2003-02-15_File_000001.jpg
c:\images\2003-02-15_File_000002.jpg
c:\images\2003-02-15_File_000003.jpg
...

2. Video stream to single image file conversion

This example shows a filter configuration that takes a video stream from a firewire camera, segments the greyscale video and saves the resulting images as TIFF files onto disc.

Image File Renderer Sample DirectShow Filter Graph
Video stream to single image file conversion