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Discussion Groups | Image Signal Processing | how to eliminate brightness variations?
Technical Discussions related to Image Processing (image coding, compression, digital effects, mpeg, etc)
how to eliminate brightness variations? - venk...@yahoo.co.in - Jan 10 4:15:00 2006
hi all,
we are doing a project titled automatic currency identification system
. in that while taking photos using web camera we were not able to
illuminate all the spot with equal brightness.we are using one of RGB
as background. while converting that image in to matrix form we are
getting wide range of values for background due to brightness
variations . but we like to use the technique of eliminating
background for which we need constant value in matrix for background.
so suggest some technique to eliminate background and to overcome the
brightness problem.
thank you
do reply,
venkatesh
(You need to be a member of imagedsp -- send a blank email to imagedsp-subscribe@yahoogroups.com )
Re: how to eliminate brightness variations? - mvgkbhat - Jan 11 10:11:00 2006
Hi Venkatesh,
Using Luminance information instead of one of RGB and finding a
histogram(equalization) of the luminance values might help you in
overcoming the problem.
Venugopala Krishna M On 1/10/06, venkatesh_aim@venk... <venkatesh_aim@venk...> wrote:
>
> hi all,
> we are doing a project titled automatic currency identification system
> . in that while taking photos using web camera we were not able to
> illuminate all the spot with equal brightness.we are using one of RGB
> as background. while converting that image in to matrix form we are
> getting wide range of values for background due to brightness
> variations . but we like to use the technique of eliminating
> background for which we need constant value in matrix for background.
> so suggest some technique to eliminate background and to overcome the
> brightness problem.
> thank you
> do reply,
> venkatesh
(You need to be a member of imagedsp -- send a blank email to imagedsp-subscribe@yahoogroups.com )
Using Luminance information instead of one of RGB and finding a
histogram(equalization) of the luminance values might help you in
overcoming the problem.
Venugopala Krishna M On 1/10/06, venkatesh_aim@venk... <venkatesh_aim@venk...> wrote:
>
> hi all,
> we are doing a project titled automatic currency identification system
> . in that while taking photos using web camera we were not able to
> illuminate all the spot with equal brightness.we are using one of RGB
> as background. while converting that image in to matrix form we are
> getting wide range of values for background due to brightness
> variations . but we like to use the technique of eliminating
> background for which we need constant value in matrix for background.
> so suggest some technique to eliminate background and to overcome the
> brightness problem.
> thank you
> do reply,
> venkatesh
(You need to be a member of imagedsp -- send a blank email to imagedsp-subscribe@yahoogroups.com )
Re: how to eliminate brightness variations? - Ranjith Parakkal - Jan 12 8:05:00 2006
Venkatesh,
Convert RGB into YCBCR or even better HSI colour
components. The brightness component is usually
contained in the Y and the I component of the YCbCr
and HSI colour spaces respectively.
You can try using colour instead of brightness to
segment your image. Here use some background whose
colour will be very different from the possible
coin-colours that you will encounter(say green or blue
or something).
Look at the histogram of the Hue(if HSI) of the
background and look at the possible values it takes.
It should be somewhat insensitive to
brightness(although not completely). Use this
information to remnove background.
Keep us updated if this helps you.
Regards
Ranjith
--- venkatesh_aim@venk... wrote:
> hi all,
> we are doing a project titled automatic currency
> identification system
> . in that while taking photos using web camera we
> were not able to
> illuminate all the spot with equal brightness.we are
> using one of RGB
> as background. while converting that image in to
> matrix form we are
> getting wide range of values for background due to
> brightness
> variations . but we like to use the technique of
> eliminating
> background for which we need constant value in
> matrix for background.
> so suggest some technique to eliminate background
> and to overcome the
> brightness problem.
> thank you
> do reply,
> venkatesh
(You need to be a member of imagedsp -- send a blank email to imagedsp-subscribe@yahoogroups.com )
Convert RGB into YCBCR or even better HSI colour
components. The brightness component is usually
contained in the Y and the I component of the YCbCr
and HSI colour spaces respectively.
You can try using colour instead of brightness to
segment your image. Here use some background whose
colour will be very different from the possible
coin-colours that you will encounter(say green or blue
or something).
Look at the histogram of the Hue(if HSI) of the
background and look at the possible values it takes.
It should be somewhat insensitive to
brightness(although not completely). Use this
information to remnove background.
Keep us updated if this helps you.
Regards
Ranjith
--- venkatesh_aim@venk... wrote:
> hi all,
> we are doing a project titled automatic currency
> identification system
> . in that while taking photos using web camera we
> were not able to
> illuminate all the spot with equal brightness.we are
> using one of RGB
> as background. while converting that image in to
> matrix form we are
> getting wide range of values for background due to
> brightness
> variations . but we like to use the technique of
> eliminating
> background for which we need constant value in
> matrix for background.
> so suggest some technique to eliminate background
> and to overcome the
> brightness problem.
> thank you
> do reply,
> venkatesh
(You need to be a member of imagedsp -- send a blank email to imagedsp-subscribe@yahoogroups.com )