MATLAB Answers

Mao Ye

imshow 16 bit tif file turns to black

Asked by Mao Ye
on 23 Jan 2017
Latest activity Commented on by Mao Ye
on 23 Jan 2017
I am currently loading a tif file into matlab by using the code below.
fname = '1.tif'; img = imread(fname); imshow(img)
But it showed a black picture. If I change to this.
fname = '1.tif'; [img,map] = imread(fname,k); imshow(img,map)
It works. And I found that map is actually empty.
If I did like this, it also works.
fname = '1.tif'; img = imread(fname); map = []; imshow(img,map)
I am wondering why.
The tif file information is here.
FileModDate: ' '
FileSize: 761533941
Format: 'tif'
FormatVersion: []
Width: 630
Height: 630
BitDepth: 16
ColorType: 'grayscale'
FormatSignature: [73 73 42 0]
ByteOrder: 'little-endian'
NewSubFileType: 2
BitsPerSample: 16
Compression: 'Uncompressed'
PhotometricInterpretation: 'BlackIsZero'
StripOffsets: 1x105 Double
SamplesPerPixel: 1
RowsPerStrip: 6
StripByteCounts: 1x105 Double
XResolution: []
YResolution: []
ResolutionUnit: 'Inch'
Colormap: []
PlanarConfiguration: 'Chunky'
TileWidth: []
TileLength: []
TileOffsets: []
TileByteCounts: []
Orientation: 1
FillOrder: 1
GrayResponseUnit: 0.0100
MaxSampleValue: 65535
MinSampleValue: 0
Thresholding: 1
Offset: ...
ImageDescription: ...
PageNumber: ...
UnknownTags: [4x1 struct]
Thank you so much. Any suggestions will be welcomed.


Can you attach '1.tif' image please
Sure. Because this is a big file. I am gonna show you one picture.

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1 Answer

 Accepted Answer

I think that it happends because your tif image is a grayscale image are it's said in properties. Maps are used for colour images.
Since it's a grayscale image the notation [] means that the display range is [min max] then you see the whole gray scale.
Check this to see how maps work on a RGB tif image.
[X,map] = imread('corn.tif');

  1 Comment

Thank you very much. I think I got the idea. It just happens that map is empty. And I should use [] to have a big contrast to show this image. Another question is I have a stack of images this. If Each picture I showed is in [min max]. It look very strange. What should I do?

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