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To accomplish this, we will need to take advantage of the IDM by initializing the input and output streams. At the start ofthe function, two instantiations of a new structure dstr_t are declared. You can view the structure contents of dstr_t on p. 2-11 of the IDK Programmer's Guide . The structure contents are defined with calls to dstr_open() . This data flow for the pre-scale is shown in data flow .

Data flow of input and output streams.

To give you a better understanding of how these streams are created, let's analyze the parameters passed in the first callto dstr_open() :

External address: in_image->data

This is a pointer to the place in memory serving as the source of our input data (it's the source because the lastfunction parameter is set to DSTR_INPUT ).

External size: (rows + num_lines) * cols = (240 + 2) * 640

This is the total size of our input data. We will only be taking every other line from in_image->data , so only 240 rows. The extra two rows are for buffer.

Internal address: int_mem

This is a pointer to an 8x640 lexographic array, specifically scratchpad->int_data . This is where we will be putting the data on each call to dstr_get() .

Internal size: 2 * num_lines * cols = 2 * 2 * 640

The size of space available for data to be input into int_mem from in_image->data . Because double buffering is used, num_lines is set to 2.

Number of bytes/line: cols = 640, number of lines: num_lines = 2

Each time dstr_get() is called, it will return a pointer to 2 lines of data, 640 bytes inlength.

External memory increment/line: stride*cols = 1*640

Left as an exercise.

Window size: 1 for double buffered

The need for the window size is not really apparent here. It will become apparent when we do the 3x3 blockconvolution. Then, the window size will be set to 3. This tells the IDM to send a pointer to 3 lines of data when dstr_get() is called, but only increment the stream's internal pointer by 1 (instead of 3) the next time dstr_get() is called. This is not a parameter when setting up an output stream.

Direction of input: dstr_input

Sets the direction of data flow. If it had been set to DSTR_OUTPUT (as done in the next call to dstr_open() ), we would be setting the data to flow from the Internal Address to the External Address.

Once our data streams are setup, we can begin processing by calling the component function pre_scale() (in pre_scale.c ) to operate on one block of data at a time. This function will perform the horizontal scaling byaveraging every two pixels. This algorithm operates on four pixels at a time. The entire function is iterated within pre_scale_image() 120 times, which is the number of rows in each quadrant. Before pre_scale_image() exits, the data streams are closed, and one line is added to the top and bottom of theimage to provide context necessary for the next processing steps. Now that the input image has been scaled to a quarterof its initial size, we will proceed with the four image processing algorithms. In img_proc.c , the set_ptr() function is called to set the variable out_ptr to point to the correct quadrant on the 640x480 output image. Then copy_image() , copy_image.c , is called, performing a direct copy of the scaled input image into the lower right quadrant of theoutput.

Questions & Answers

what is the stm
Brian Reply
is there industrial application of fullrenes. What is the method to prepare fullrene on large scale.?
industrial application...? mmm I think on the medical side as drug carrier, but you should go deeper on your research, I may be wrong
How we are making nano material?
what is a peer
What is meant by 'nano scale'?
What is STMs full form?
scanning tunneling microscope
how nano science is used for hydrophobicity
Do u think that Graphene and Fullrene fiber can be used to make Air Plane body structure the lightest and strongest. Rafiq
what is differents between GO and RGO?
what is simplest way to understand the applications of nano robots used to detect the cancer affected cell of human body.? How this robot is carried to required site of body cell.? what will be the carrier material and how can be detected that correct delivery of drug is done Rafiq
what is Nano technology ?
Bob Reply
write examples of Nano molecule?
The nanotechnology is as new science, to scale nanometric
nanotechnology is the study, desing, synthesis, manipulation and application of materials and functional systems through control of matter at nanoscale
Is there any normative that regulates the use of silver nanoparticles?
Damian Reply
what king of growth are you checking .?
What fields keep nano created devices from performing or assimulating ? Magnetic fields ? Are do they assimilate ?
Stoney Reply
why we need to study biomolecules, molecular biology in nanotechnology?
Adin Reply
yes I'm doing my masters in nanotechnology, we are being studying all these domains as well..
what school?
biomolecules are e building blocks of every organics and inorganic materials.
anyone know any internet site where one can find nanotechnology papers?
Damian Reply
sciencedirect big data base
Introduction about quantum dots in nanotechnology
Praveena Reply
what does nano mean?
Anassong Reply
nano basically means 10^(-9). nanometer is a unit to measure length.
do you think it's worthwhile in the long term to study the effects and possibilities of nanotechnology on viral treatment?
Damian Reply
absolutely yes
how to know photocatalytic properties of tio2 nanoparticles...what to do now
Akash Reply
it is a goid question and i want to know the answer as well
characteristics of micro business
for teaching engĺish at school how nano technology help us
How can I make nanorobot?
Do somebody tell me a best nano engineering book for beginners?
s. Reply
there is no specific books for beginners but there is book called principle of nanotechnology
how can I make nanorobot?
what is fullerene does it is used to make bukky balls
Devang Reply
are you nano engineer ?
fullerene is a bucky ball aka Carbon 60 molecule. It was name by the architect Fuller. He design the geodesic dome. it resembles a soccer ball.
what is the actual application of fullerenes nowadays?
That is a great question Damian. best way to answer that question is to Google it. there are hundreds of applications for buck minister fullerenes, from medical to aerospace. you can also find plenty of research papers that will give you great detail on the potential applications of fullerenes.
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Source:  OpenStax, Ece 320 - spring 2003. OpenStax CNX. Jan 22, 2004 Download for free at http://cnx.org/content/col10096/1.2
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