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Questions tagged [contrast]

the difference in color and light between parts of an image

281 questions
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contrast and brightness automatic (for OCR)

I'm looking for an algorithm to adjust automatically contrast and brightness for images that after will be scanned by Tesseract (an OCR engine). Do you know if is it possible?
malilzap
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How to control the contrast of text?

How do you change the color contrast of text when the background changes? for example If I was to have a black background, black text would not be visible.
ahodder
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How extract contrast level of a photo - opencv

I need to return the (average) contrast value of an image. Is this possible and if so, please show how? More than just the code, (obviously the code is welcome), in what color space should I work? Is HSV appropriate or best? Can the contrast value…
Da Nio
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I want to increase brightness and contrast of images in dynamic way so that the program is applicable for any new images

I have few images where I need to increase or decrease the contrast and brightness of the image in a dynamic way so that it is visible clearly. And the program needs to be dynamic so that it even works for new images also. I also want character…
Ani
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1 answer

Passing a list of contrasts read as characters to a linear mode in R

Probably missing something basic here. I have XY data to which I want to fit an lm in R: set.seed(1) df <- data.frame(x = c("0h","0h","4h","4h","8h","8h","10h","10h"), y = rnorm(8)) Fitting the lm is part of a function that…
dan
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Calculate contrast of a color image(RGB)

In black and white image,we can easily calculate the contrast by (total no. of white pixels - total no. of black pixels). How can I calculate this for color(RGB) image? Any idea will be appreciated?
Image
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Contrast requirements for WCAG level A?

I am trying to adapt an older website to become accessible. However, the first tests with browser tools like "WAVE" showed me contrast errors for headers which are simply colored text on white background. The colors are #97CB44 (a lighter green) and…
Johannes
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Python: Evaluate image (video) contrast

For my project I need a plot showing how the quality of contrast in a video changes over time. At the moment I'm calculating the CDF of the image histogram for every frame - now I need to translate this into some kind of percentage/quality…
2092Juli
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model.matrix and makeContrasts in R

I would like to do some contrasts via linear regression modeling in R. I have the following data, mat1: Gene1 Gene2 Gene3 1 5.89 7.45 2.66 2 8.99 5.39 1.58 3 3.67 6.88 4.82 4 8.25 8.76 3.58 I use the…
Melanie Julia
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change the contrast of an image in DM Scripting

I need to change the contrast of an image by using a script, unfortunately I don't know how to do it, maybe you can help me. I've searched the help documents, but the results do not give the right answer Thanks.
Fabian V.
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Improving Low Contrast Image Segmentation

I have phase-contrast microscopy images that needs to be segmented. It seems very difficult to segment them due to the lack of contrast between the objects from the background (image 1). I used the function adapthisteq to increase the visibility of…
Senyokbalgul
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what are the limits for IMG_FILTER_CONTRAST imagefilter

I am working on php gd image filters. Grayscale, Brightness, Negate, Colorize works well, but trying imagefilter($img, IMG_FILTER_CONTRAST, $level); I found it somewhat ambiguous. The level limits for contrast are not clearly mentioned at the php…
bantya
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How to do contrast stretching in opencv or numpy?

I'm trying to stretch the contrast of an opencv3 / numpy.ndarray picture in my Python 3 application. I found the normalize method, but that seems to do the opposite, pushing 1 to 255 in the range 10 to 11 for example. In numpy i found nothing easy,…
xuiqzy
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Image brightness contrast seekbar

I am developing an app, that i want to implement some "filters" like contrast/brightness/hue etc. All these changes i want to get done through seekbar valuechanged. All of examples found here, are not smooth at all for realtime change through…
Margitoudis Konstantinos
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Print a-priori contrasts with type III sums of squares using Anova() in R

I am trying to print a-priori contrasts with type III sums of squares results. (Please don't speak about type I vs. type III. That's not the point of my question.) I can print the contrasts like I need using summary.aov(), however that uses type…
Rachael Blake
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