ImageAdjust

ImageAdjust[image]

adjusts the levels in image, rescaling them to cover the range 0 to 1.

ImageAdjust[image,corr]

adjusts the image according to the correction specification corr.

ImageAdjust[image,corr,{inmin,inmax}]

first rescales so that the range of input values inmin to inmax is mapped to 0 to 1.

ImageAdjust[image,corr,{inmin,inmax},{outmin,outmax}]

rescales so that the range of input values inmin to inmax is mapped to outmin to outmax.

Details

  • ImageAdjust can be used for adjusting pixel values so that more of the image content is in the visible range or to correct for bad illumination or contrast.
  • ImageAdjust works with arbitrary 2D and 3D images.
  • Correction corr for contrast, brightness and gamma correction can take any of the following settings:
  • cadjusts the image contrast by c
    {c,b}also adjusts the image brightness by b
    {c,b,γ}also performs a gamma correction by raising the values to the power of γ
  • The correction transformation applied to every pixel value x is , rounded or clipped to the image type, if necessary.
  • Zero adjustment corresponds to {0,0,1} correction.
  • When rescaled values lie outside the range outmin to outmax, they are clipped.
  • All correction and range parameters can be given as lists to specify different treatment for different channels in the image. »
  • Range parameters can be set to Automatic to indicate the minimum or maximum of the values that occur in the image.
  • When applied to color images, ImageAdjust always returns an RGB image.

Examples

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Basic Examples  (2)

Auto adjust values of a color image:

Adjust the brightness of a color image:

Scope  (9)

Data  (3)

Adjust the brightness of a 2D grayscale image:

Perform a gamma correction on a color image:

Auto-adjust a 3D image:

Contrast  (2)

Increase the contrast of an image:

Decrease the contrast:

Increase the contrast in the blue channel only:

Brightness  (1)

Increase the brightness of an image:

Make an image darker:

Increase the contrast and brightness of an image:

Gamma  (1)

Adjust a color image using different gamma values:

Scaling  (2)

Adjust the input range:

Adjust the input range using channel-specific settings:

Applications  (7)

Create a high-contrast image:

Use gamma values in the range 0<γ<1 to see more details in dark areas of an image:

Use values γ>1 to see more details in a washed-out image:

Adjust to see relative distances returned by DistanceTransform:

Adjust to see out-of-range values returned by LaplacianGaussianFilter:

Symmetrically adjust the result of a Laplacian filter:

Use the maximum range in each channel:

Compare with the default adjustment:

Adjust the brightness of a region of interest in an image:

Create a mask:

Enhance the image:

Adjust very small values in a 3D image:

Properties & Relations  (5)

For grayscale images, ImageAdjust[Image[data]] is equivalent to Image[Rescale[data]]:

ImageAdjust[image] is equivalent to ImageAdjust[image,{0,0,1},{min,max},{0,1}], where {min,max} are the channel-wise pixel ranges in image:

ImageAdjust[image,-2] is equivalent to ColorNegate[image]:

ImageAdjust[image,-1] returns a constant image:

Image contrast increases as contrast value c is varied from -1 to ∞:

ImageAdjust[image,{c,b,γ}] is equivalent to ImageApply[Clip[(b+1)(c+1)#γ-c/2,{0,1}]&,image]:

When scaling is specified, it is applied before the other corrections:

The image is not changed if the input and the output range are identical:

View the pixel transformation function and its effect on the example image and its histogram as the contrast, brightness and gamma parameters are changed:

Possible Issues  (2)

Noise may get amplified for images with small color variation:

ImageAdjust may introduce new colors, as all channels are scaled independently:

Perform a global adjustment:

Wolfram Research (2008), ImageAdjust, Wolfram Language function, https://reference.wolfram.com/language/ref/ImageAdjust.html (updated 2019).

Text

Wolfram Research (2008), ImageAdjust, Wolfram Language function, https://reference.wolfram.com/language/ref/ImageAdjust.html (updated 2019).

CMS

Wolfram Language. 2008. "ImageAdjust." Wolfram Language & System Documentation Center. Wolfram Research. Last Modified 2019. https://reference.wolfram.com/language/ref/ImageAdjust.html.

APA

Wolfram Language. (2008). ImageAdjust. Wolfram Language & System Documentation Center. Retrieved from https://reference.wolfram.com/language/ref/ImageAdjust.html

BibTeX

@misc{reference.wolfram_2024_imageadjust, author="Wolfram Research", title="{ImageAdjust}", year="2019", howpublished="\url{https://reference.wolfram.com/language/ref/ImageAdjust.html}", note=[Accessed: 22-November-2024 ]}

BibLaTeX

@online{reference.wolfram_2024_imageadjust, organization={Wolfram Research}, title={ImageAdjust}, year={2019}, url={https://reference.wolfram.com/language/ref/ImageAdjust.html}, note=[Accessed: 22-November-2024 ]}