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Questions tagged [luminance]

64 questions
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How to get camera brightness from Vuforia?

I'm using Vuforia SDK for AR. I need to get the luminance from the device camera. I searched on Vuforia forum but couldn't find anything there. How can I get the camera light intensity from Vuforia SDK?
Nuibb
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How to detect frames to keep or discard based on luminosity levels?

I have a series of images from a slow motion capture of pulsing electrical discharges. Many of the frames are nearly black. I would like to selectively keep the frames that are more interesting; eg have more luminosity. I've considered using…
ylluminate
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Gamma Correction and Luminance Masking

As per Weber's law, delta(L)/L is a constant where L is luminance measured in candela/m2 )i.e. (L2 - L1)/L1. This implies that a small change in lower luminance range (darker) is perceptually much more than a small change in higher luminance range…
Pranav Sodhani
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Imageview not resetting to original after sharpness filter used

Not able to get original image after applying the filter on imageview.As I want to get original image after moving the slider from 1 to 0 (max to min value, I mean in reverse direction). Below is the code for applying sharpness effect -…
jyotsna pandey
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Adjusting Luminance of a Color in Stylus

I'm working with Stylus, the CSS Pre-processor and I want a function to adjust the "perceived brightness" of the color, say, by 20% or -10%. I discovered the term "luminance", and it looks like Stylus has a function to get the luminance of a color,…
Petter Thowsen
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Luminance 'y' value of surface texture

For my opengl video player app, I am using surface texture bound to GL_TEXTURE_EXTERNAL_OES source : https://github.com/crossle/MediaPlayerSurface/blob/master/src/me/crossle/demo/surfacetexture/VideoSurfaceView.java In my fragment shader, I want…
deeps8us
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Zxing construcing binarybitmap from a gray scale image android

i am developing an android application it has a requirement of decoding gray scale images which contains qr codes. i have been trying to integrate zxing with android . for rgb color scale images it's working fine. for rgb image byte array i have…
Dinesh Kannan
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Setting luminance for manually-defined color pallets in ggplot2

I have a custom color pallet I'd like to use for a geom_bar plot. However I'd also like to set the luminance of these colors manually. When I run the scale_fill_manual() and scale_fill_hue() functions together in my ggplot code, I get the…
Luke
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Sass function for determining the luminance of a color

I've found a half-dozen functions online for determining the luminance of a color in Sass. They are all almost identical, but none of them are working - all throwing the same error: invalid operands for multiplication This is the function I am…
Greg Jenkins
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Batch change image Luminosity in Photoshop

I have about 2000 images with different values of luminosity. I can, of course, open each one and manually change Luminosity until it reaches my desired value (200), but of course when you have 2000 images that's not an option. It seems I can't…
André Silva
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Get texture coords on screen OpenGL

I'm trying to create a tone-mapping operator that changes on real time. I have the LDR image (after apply the operator to the HDR image) on a spherical texture, on a sphere which always rotates about Y axis, and the camera is inside the sphere; here…
MikeFadeCrew
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jpeg encoder generates wrong luminance values

I am currently developing a dct based jpeg encoder and got stuck on a problem with the luminance channel. The chrominance values seem to be correct. A few words to the encoding procedure. The picture is based on ycbcr color values. Cb and Cr Channel…
xSmorpheusSx
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Luminance of 8 * 8 block

Is there a c++ function or an opencv library that can calculate the average log of the luminance of a given 8*8 block or total image? My aim is to calculate the average luminance and store it back in the block. Also, is there another way to…
user3601375
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Get new HSL Color by lumMod/lumOff

Am I doing this correctly? For example, I have an RGB(165,165,165) and convert it to the HSL(Get (0, 0, 64.7)). Actually I parse xml, and there I have two parameters lumMod = '60 000' and lumOff = '40 000' (As I know it means that I must multiply…
Maxim Banaev
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Recreating the effect by using replace color in photoshop

I adjusted my image by using photoshop's replace color tool and changing the hue, saturation, and lightness sliders. Unfortunately I forgot the individual settings for each and I need to recreate the effect. I tried eye balling it and can't seem to…
David Zhang
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