demosaic
Convert Bayer image to truecolor image
Syntax
Description
RGB = demosaic(bayer,sensorAlignment)bayer, to the
truecolor image, RGB. The
sensorAlignment argument specifies the
Bayer pattern.
A Bayer filter mosaic is a type of color filter array (CFA), or an arrangement of color filters on the photosensors of a single-chip digital camera. The color filters let each photosensor record only red, green, or blue data. A Bayer pattern is the repeating arrangement of the four color filters, consisting of two green, one red, and one blue filter, that comprise the Bayer filter mosaic.
A Bayer pattern image, or Bayer image, is the image captured by a camera with a Bayer filter mosaic. Demosaicing a Bayer image consists of combining the signals from the photosensors to form a 3-channel truecolor image, rather than a single-channel intensity image.
RGB = demosaic(bayer,sensorAlignment,BitsPerSample=bitsPerSample)bitsPerSample, of the input Bayer
image. Use this syntax when the data contains fewer bits than the
data type (since R2025a).
Examples
Convert a Bayer pattern encoded image that was photographed by a camera with a sensor alignment of 'bggr'.
I = imread("mandi.tif"); J = demosaic(I,"bggr"); imshow(I)
imshow(J)
Read a color filter array (CFA) image and the metadata from a RAW file. This data was captured using a 12-bit sensor and is stored using data type uint16.
file = "colorCheckerTestImage.NEF";
cfa = rawread(file);
info = rawinfo(file);To verify that this is 12-bit data, check the maximum pixel value. The maximum value is within the range of 12-bit data (2^12-1, or 4095).
maxValue = max(cfa(:))
maxValue = uint16
3366
The file metadata, which includes information about the value of white pixels, is also consistent with 12-bit data.
whiteValue = info.ColorInfo.WhiteLevel
whiteValue = 1×4 uint16 row vector
3827 3827 3827 3827
Get the Bayer pattern from the metadata. Demosaic the image using 12 bits per sample.
sensorAlignment = info.CFALayout; rgbout = demosaic(cfa,sensorAlignment,BitsPerSample=12); imageshow(rgbout,DisplayRange=[0 2^12])
Input Arguments
Bayer pattern encoded image, specified as an
M-by-N
numeric array. bayer must have
at least 5 rows and 5 columns.
Data Types: uint8 | uint16 | uint32
Bayer pattern, specified as one of the values in the following table. Each value represents the order of the red, green, and blue sensors by describing the four pixels in the upper-left corner of the image (left-to-right, top-to-bottom).
| Pattern | 2–by-2 Sensor Alignment |
|---|---|
"gbrg" |
|
"grbg" |
|
"bggr" |
|
"rggb" |
|
Data Types: char | string
Since R2025a
Bits per sample, specified as a positive integer. The
maximum value of the demosaiced image
RGB is equal to 2^bitsPerSample –
1.
By default, bitsPerSample is
equal to the number of bits of the data type of
bayer: 8
for uint8 images,
16 for
uint16 images, and
32 for
uint32 images.
Example: 12 uses 12 bits per sample
and sets the maximum value of the RGB image to 2^12
– 1, or 4095, for uint16 and
uint32 Bayer
images.
Output Arguments
Algorithms
The demosaic function uses gradient-corrected linear
interpolation to convert the two-dimensional Bayer image into the truecolor
image.
References
[1] Malvar, H.S., L. He, and R. Cutler, High quality linear interpolation for demosaicing of Bayer-patterned color images. ICASPP, Volume 34, Issue 11, pp. 2274-2282, May 2004.
