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Once a stream is created, you can use the get and put commands in a loop, to bring in or put out line/s of data. Calling dstr_get on an input stream will give you a buffer where data is present to be read off. And calling an output stream will give you a buffer to which you can write data (which will be transported out on the next dstr_put call).

Remember, you have to be careful how many times you call these functions as you so not want to overflow. For example in our output example, we could call the dstr_put() upto 480 times – the number of single row transfers. Anymore, and the system may crash.

Also please remember to close the stream once you are done with it, i.e after all iterations. See the color_convert function to see when we close the streams using dstr_close(…). This is VERY important, since not closing a stream will cause random crashing of your system. The system may seem to run as you expected, but it will crash, if not after 1 second, then after 1 minute or 1 hour. This problem is one of the first you should look for when debugging such symptoms.

Also take a look at the streams for the input color components YCbCr to see how they are setup. You will find the figure on Device Driver Paper page 3-8 very useful in deciphering these streams. Understand them and you are set!

Quick-Test: Write a stream to obtain one-line buffers for columns 31 through 50 (20 columns) of the output buffer, with 50 rows. This rectangular region should start at pixel (100, 200). So each transfer should give a buffer of 20 * 2 bytes worth of information. Think of how you’d setup the stream.

Memory tricks and tips

Some simple memory tips are given here, you can come up with your own too.

  • Know how data flows in your system, this will help you increse efficiency and possibly eliminate complex stream use as well.
  • The dstr_get_2D and dstr_put_2D are used for multiple line transfers. Use these to your advantage.
  • You can use a simple memory ping-pong system to lessen memory use. If you need to use, say 200 X 300 rectangular region and filter it repeatedly. Then keep two memory 200 X 300 memory spaces. Write to the first, filter out to the second. Then filter the second out to the first, and so on until you're done.

Limitations

  • Space is a always a factor, especially with internal memory.
  • It's harder to extract columns of data as opposed to rows. To transfer a column, you need to setup a different stream, one that skips a whole ‘row-1’ of data with each dstr_get statement. Then you will need to iterate this to get the pixel on each row of that column. Multiple get's are necessary because the data is not contiguous in memory.

Idk libraries

To make your life easier, the IDK has some libraries which you can use for common image processing tasks. One such function is the Sobel (edge-detect) filter. These functions are usually hand coded in assembly and are extremely efficient, so it's best not to try to beat them.

The Sobel filter is contained in the file 'sobel_h.asm' and the header file needed is 'sobel_h.h'. You must add the program file and it's header in the project to use them. Next you will need to create a wrapper function and use the #include "sobel_h.h" directive in the wrapper function at the top. Don't forget to create a header function for your wrapper as well and add it to your project.

Next you will need to setup the streams and provide the assembly function the needed parameters. Namely, it needs a pointer to 3 lines worth of input data to be processed, one line of output data, the number of columns and number of rows. The library Sobel filter works on 3 lines of input and produces 1 line of output with each call. Look at the 'sobel_h.asm' to get a better understanding of the parameters

This material should be familiar from the previous lab where we explored wrapper and component functions. Now time for the assignment!

The assignment

Your assignment, should you choose to accept it is to build a simple filter system. You will start with the basic color conversion program given to you in: V:\ece320\projects\colorcool The system will copy the red-component of a 100 by 100 area of the screen (let’s call this area M). It will place this in a different area of the screen. Also you will need to place a Sobel filtered version of this red-area to the screen as well. The locations where the copied and filtered images are placed must be quickly modifiable on request (use variable position as parameters to wrapper functions rather than fixed coordinates)

Tips, tricks and treats

  • Plan the system before hand to make efficient use of modular functions and memory
  • For example, you only need just one “output area if size M” function to screen.
  • Keep handy pointers to the different memory spaces.
  • Use wrapper functions for the filter and copy_to_screen operations.
  • Write the modules so that they can be tested independently.
  • Be careful with color conversion. For example when copying the red-component of M, you need only 8 bits per pixel.
  • Keep the previous lab in mind when deciding when/where to extract the area M.

Questions & Answers

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
?
Kyle
yes I'm doing my masters in nanotechnology, we are being studying all these domains as well..
Adin
why?
Adin
what school?
Kyle
biomolecules are e building blocks of every organics and inorganic materials.
Joe
anyone know any internet site where one can find nanotechnology papers?
Damian Reply
research.net
kanaga
sciencedirect big data base
Ernesto
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.
Bharti
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
Daniel
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
Maciej
characteristics of micro business
Abigail
for teaching engĺish at school how nano technology help us
Anassong
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
NANO
what is fullerene does it is used to make bukky balls
Devang Reply
are you nano engineer ?
s.
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.
Tarell
what is the actual application of fullerenes nowadays?
Damian
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.
Tarell
what is the Synthesis, properties,and applications of carbon nano chemistry
Abhijith Reply
Mostly, they use nano carbon for electronics and for materials to be strengthened.
Virgil
is Bucky paper clear?
CYNTHIA
carbon nanotubes has various application in fuel cells membrane, current research on cancer drug,and in electronics MEMS and NEMS etc
NANO
so some one know about replacing silicon atom with phosphorous in semiconductors device?
s. Reply
Yeah, it is a pain to say the least. You basically have to heat the substarte up to around 1000 degrees celcius then pass phosphene gas over top of it, which is explosive and toxic by the way, under very low pressure.
Harper
Do you know which machine is used to that process?
s.
how to fabricate graphene ink ?
SUYASH Reply
for screen printed electrodes ?
SUYASH
What is lattice structure?
s. Reply
of graphene you mean?
Ebrahim
or in general
Ebrahim
in general
s.
Graphene has a hexagonal structure
tahir
On having this app for quite a bit time, Haven't realised there's a chat room in it.
Cied
what is biological synthesis of nanoparticles
Sanket Reply
what's the easiest and fastest way to the synthesize AgNP?
Damian Reply
China
Cied
how did you get the value of 2000N.What calculations are needed to arrive at it
Smarajit Reply
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Source:  OpenStax, Digital signal processing laboratory (ece 420 55x). OpenStax CNX. Jan 18, 2010 Download for free at http://cnx.org/content/col10397/1.10
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