how to compensate for low dynamic range monitors?

Started by kiki in comp.dsp14 years ago 2 replies

Hi all, I have a bright image which is taken using good camera, and I upsampled it to a higher resolution(say NxN larger size)... and then...

Hi all, I have a bright image which is taken using good camera, and I upsampled it to a higher resolution(say NxN larger size)... and then applied some image processing, color space conversion, gamma transformation, inverse gamma, filtering, etc... and the new image look dark...(or equavalent, the LCD monitor does not support the new image due to its limited dynamic range... what can ...


how does matlab zero pad on fft

Started by CDB in comp.dsp15 years ago 3 replies

hello, i am trying to compare my versus matlab's implementaion of a convolution in the frequency domain. i have a mask that is not the...

hello, i am trying to compare my versus matlab's implementaion of a convolution in the frequency domain. i have a mask that is not the same size of the image (in fact its much smaller). but i fft2 the mask with the dimensions of the image and then convolve with the fft2 of the image. my question i, what method is used for zero padding the mask to be the same size of the image? can...


Image search

Started by KK in comp.dsp11 years ago 1 reply

I'm trying to implement the image search described here http://www.dspguide.com/ch24/6.htm. I have to check for existence of a target image....

I'm trying to implement the image search described here http://www.dspguide.com/ch24/6.htm. I have to check for existence of a target image. Upon convolution we will have some values, each value proportional to the match. There may one or more maximas depending on repetition of the target. so is the case If target does not exist in the source image.Although in the latter case, values will be...


4:2:2 to 4:4:4 conversion

Started by Ajay in comp.dsp14 years ago 2 replies

Hi, I have subsampled 4:4:4 image using 15-tap filter into 4:2:2 image. Now, in order to view 4:2:2 image, I need to convert it back into...

Hi, I have subsampled 4:4:4 image using 15-tap filter into 4:2:2 image. Now, in order to view 4:2:2 image, I need to convert it back into 4:4:4 image. I have repeated the chroma samples to create chroma values for alternate luma samples erstwhile without chroma. However, I am doubtful of the method. Do I need to interpolate to create the missing chroma samples? What is generally done in su...


Regarding DCT

Started by jyothina in comp.dsp12 years ago 1 reply

Hi All, I am performing Integer DCT on Lena image. I am using " C "& i am not able to reconstruct the image correctly. Before applying DCT I...

Hi All, I am performing Integer DCT on Lena image. I am using " C "& i am not able to reconstruct the image correctly. Before applying DCT I am subtracting 128 from all pixels of input image. After IDCT i am adding 128 to the result image. I want to compare my results with MATLAB . Is anybody know how to use dct i.e. dct2 function of MATLAB? if anyone has the related code in MATLAB please...


even/odd symmetry in 2D FT of real-valued image

Started by Chris Bore in comp.dsp13 years ago 3 replies

Hi folks, If I have a 2D image whose values are purely real, and I take the 2D FT, then I expect the 2D FT to have even symmetry. I think this...

Hi folks, If I have a 2D image whose values are purely real, and I take the 2D FT, then I expect the 2D FT to have even symmetry. I think this applies to a reflection about one axis - that is, half the resulting 2D FT image is a reflection of the other half. So all the information is in kept if I use just one half of the 2D FT image. But does it apply in some circumstances to each quadra...


Image-reject IF downmixing

Started by Kevin Neilson in comp.dsp15 years ago 6 replies

When digitally mixing an IF down to baseband, one is left with a spectrum that consists of the baseband (Fif - Fmix = 0Hz) and an image (Fif +...

When digitally mixing an IF down to baseband, one is left with a spectrum that consists of the baseband (Fif - Fmix = 0Hz) and an image (Fif + Fmix). If the IF is greater than the Nyquist freq, the image will wrap back into the first Nyquist zone (0 to Fn). Normally the next step in demodulation is decimation, which consists of lowpass filtering out the image (often with CICs) and then drop...


Newbie question

Started by Skice in comp.dsp13 years ago 1 reply

I have a 2d signal (an image, actually) of which I want to calculate ACF. I tried to use the IFFT/FFT approach, but when I rotate the image...

I have a 2d signal (an image, actually) of which I want to calculate ACF. I tried to use the IFFT/FFT approach, but when I rotate the image I notice some strange effects (something aliasing-like). So I tried to pad my image both vertically and horizontally with zeros, doubling its dimension before calculating the FFT. Am I doing right? Someone can help me? Thank you Lorenzo


image filtering using bessel function/filters

Started by cedance in comp.dsp12 years ago 16 replies

Hi, I have been asked to design a program in Matlab which calculates the FFT of an image, then defocus the image using a Bessel filter, and...

Hi, I have been asked to design a program in Matlab which calculates the FFT of an image, then defocus the image using a Bessel filter, and reconstruct the defocussed image. Now, I find that only analog models of Bessel filters are available in Matlab, though i found a link to a pdf which shows values of the coefficients upto order 10. But, how do i construct a 2D-Bessel Digital filter? I a...


problem displaying YUV image on Code composer studio

Started by dokang in comp.dsp13 years ago 1 reply

I'm trying to display the picture that the dskCam takes on Code composer studio. However, the image that i see on Code composer studio(view->...

I'm trying to display the picture that the dskCam takes on Code composer studio. However, the image that i see on Code composer studio(view-> graph-> image) doesnt seem to be right. I captured the screeen which shows the image, and you can check that here -> http://www-personal.umich.edu/~dokang/image.bmp fllowings are parts of my code that i'm using. -> http://www-personal.umich.e


how to estimate the additive noise and get rid of additive noise in image?

Started by kiki in comp.dsp15 years ago 7 replies

Hi all, I obtained some pictures using camera. It looks to me there are some additive noise that was added to all image pixel components:...

Hi all, I obtained some pictures using camera. It looks to me there are some additive noise that was added to all image pixel components: from what I've observed, there are many small fluctuations/peaks/spikes of height 10-30, while the useful image region has values about 300. I am afraid that such noise has also been added to the useful image region, so the images have been univers...


Image segmenation using gabor wavelets - help needed.

Started by drackz in comp.dsp11 years ago

Hi friends, i am dinesh. i am doing texture analysis and image segmenatation using gabor wavelets in java.. so far i have successfully...

Hi friends, i am dinesh. i am doing texture analysis and image segmenatation using gabor wavelets in java.. so far i have successfully finished doing texture analysis using gabor wavelets.. now i have to do image segmentation.... actually my work is decamouflaging, that is multiple camouflage breaking, finding the objects that are hidden in the given image because of its same texture as t...


what is the difference btwn conv2 and filter2 in matlab?

Started by fulltime in comp.dsp12 years ago 1 reply

Hi, I am trying to apply 2D FIR filters to an image. wat is the difference btwn using conv2 and filter2? When i use conv2, I can obtain an...

Hi, I am trying to apply 2D FIR filters to an image. wat is the difference btwn using conv2 and filter2? When i use conv2, I can obtain an image of the same size as the original image, but if i were to use filter2, the result is only a few pixels. another question is upon reading in an image using imread, do i need to convert to ycbcr format before i perform the conv2 or filter2? U...


understanding wavelet transform in image processing....

Started by brettcooper in comp.dsp6 years ago 7 replies

Dear Forum, I am learning about wavelets and image processing. I have seen how the wavelet transform of an image looks like: it is a bunch of...

Dear Forum, I am learning about wavelets and image processing. I have seen how the wavelet transform of an image looks like: it is a bunch of subimages that seem low pass and high pass filtered versions of the original image.... That is not what I expected the wavelet transform to look like after studying the continuous one-dimensional wavelet transform, which represents the coefficients of ...


the point of passing through a filter in image processing

Started by PZ in comp.dsp13 years ago 1 reply

Hi, I have a basic question on image processing, after FT, I got the casted image on different colors, or different freq. Next is to pass...

Hi, I have a basic question on image processing, after FT, I got the casted image on different colors, or different freq. Next is to pass through a filter to get the freq that I want. I am wondering, I can just pick up any freq I want, and the band of freq I want. Why do I have to construct a filter? Is it really needed? Or how a filter is being used in image processing? thanks PZ ...


Image Processing

Started by Robert Sherry in comp.dsp16 years ago 7 replies

I am currently a graduate student in Computer Science and I have just completed a course in image processing. I have also recently purchased...

I am currently a graduate student in Computer Science and I have just completed a course in image processing. I have also recently purchased a digital camera which produces images in JPEG. I am looking for a library that I can use to write C++ programs to manipulate the image. Does anybody know of such a library? I thank the group in advance for their responses. ...


what does phase distortion look like in image processing?

Started by lucy in comp.dsp15 years ago 7 replies

I read the following in Matlab Help Document of Image Processing ToolBoxes, "FIR filters can be designed to have linear phase, which helps...

I read the following in Matlab Help Document of Image Processing ToolBoxes, "FIR filters can be designed to have linear phase, which helps prevent distortion. " I am wondering what does phase distortion look like in image processing? Also, "Another class of filter, the infinite impulse response (IIR) filter, is not as suitable for image processing applications. It lacks the inheren...


need help about image restoration T_T

Started by bambo in comp.dsp12 years ago

hi.... first of all i would like to introduce myself... my name is johan... right now i'm doing my S1 thesis in information technology..... i...

hi.... first of all i would like to introduce myself... my name is johan... right now i'm doing my S1 thesis in information technology..... i take image restoration topic and.... i'm a newbie in this topic (so... i need a lot of help to understand about the step) and.... i use handbook : image processing theory, algorithms, & architectures by Maher A. Sid-Ahmed it is said that one of the proced...


Re: ANNOUNCEMENT: New image format

Started by Thomas Richter in comp.dsp11 years ago

John Costella schrieb: > 12:30 pm CST, November 22, 2007 > > > I am pleased to announce the release of a new image format, which I > ...

John Costella schrieb: > 12:30 pm CST, November 22, 2007 > > > I am pleased to announce the release of a new image format, which I > have somewhat mischievously dubbed "JPEG-Clear", which is optimized > for the following uses, among others: > > * Transmission of images or image sequences compressed losslessly or > lossily through a limited bandwidth channel (such as the Internet), >


FFTW, Imlib & OpenCV

Started by sunderam in comp.dsp14 years ago 28 replies

Hi there, I am working on an image processing project. I am trying to represent an image in terms of signal and then calculate contrast using...

Hi there, I am working on an image processing project. I am trying to represent an image in terms of signal and then calculate contrast using that signal representation of the image. I know that inorder to represent an image in terms of signal a FFT has to be performed. I am using FFTW to calcuate the FFT. My dilema is that i m using opencv(open computer vision lib)to do other parts of t...