A = imread(filename)
[A, map] = imread(filename)
[A, map, transparency] = imread(filename)
| Parameter | Description |
|---|---|
| filename | a row vector characters or scalar string: name of graphics file. |
| Parameter | Description |
|---|---|
| A | Image data: array. |
| map | Colormap: m-by-3 matrix. |
| transparency | Transparency information: matrix. |
imread reads the image data from the given file into a matrix.
The file type is detected from its signature. The extension is used as a fallback for textual or ambiguous formats. For animated GIF files, the first composited frame is returned; for TIFF files, the first page is returned.
Indexed images return an M-by-N uint8 matrix, a K-by-3 double colormap in [0, 1] and, when present, an M-by-N uint8 transparency matrix. RGB and RGBA images return an M-by-N-by-3 uint8 array; RGBA transparency is returned separately as the third output. Sixteen-bit grayscale PNG, TIFF and PGM images return an M-by-N uint16 matrix.
| Format | Access |
|---|---|
| BMP/DIB | read |
| GIF | read, first composited frame |
| JPEG/JFIF (JPG) | read |
| TIFF | read, first page |
| PCX | read |
| PNG | read |
| PBM | read |
| PGM | read |
| PPM | read |
| WebP, TGA, PNM | read |
| PSD, HDR/RGBE, PIC | read only |
f = figure();
filename = [tempname, '.webp'];
imwrite(rand(32, 32, 3), filename, 'Quality', 90);
img = imread(filename);
imagesc(img);
close(f);
source = rand(16, 16, 3);
alphaSource = rand(16, 16);
webpFile = [tempname, '.webp'];
png16File = [tempname, '.png'];
indexedFile = [tempname, '.png'];
imwrite(source, webpFile, 'Alpha', alphaSource);
imwrite(uint16(reshape(0:255, 16, 16) * 257), png16File);
indices = uint8([0 1; 1 0]);
palette = [1 0 0; 0 0 1];
imwrite(indices, palette, indexedFile);
[rgb, map, alpha] = imread(webpFile);
gray16 = imread(png16File);
[X, indexedMap, indexedAlpha] = imread(indexedFile);
| Version | Description |
|---|---|
| 1.0.0 | initial version |
| 1.13.0 | pcx, tiff formats added |
| 2.0.0 | WebP and deterministic Qt-free codecs added |