load_image

Builtin index · Images

result = load_image(path)

Input: path · Output: result

What it is

path is a string file path. Reads the file from disk and decodes it — PNG, BMP, JPEG and TIFF. The format is sniffed from the file's first bytes rather than its extension, because a .png that is really a BMP is a thing that happens and the bytes are never wrong. PNG: bit depths 1/2/4/8/16, colour types grey, truecolour, palette, grey+alpha and RGBA; alpha composites onto white, since Image is three channels. Adam7 interlacing is refused by name rather than decoded wrongly. JPEG: baseline and progressive, grayscale (widened to R=G=B) and colour; 16-bit and CMYK JPEGs are refused by name rather than converted, because guessing CMYK's Adobe inversion convention wrong yields silently colour-inverted pixels. TIFF: 8- and 16-bit integer samples in grayscale, grayscale+alpha, RGB and RGBA (16-bit is scaled down to 8, since Image is 8-bit; alpha composites onto white as with PNG); floating-point, palette, CMYK and YCbCr TIFFs are refused by name.

Overloads

One call shape — this function is not overloaded.

Examples

From the documentation, and run by the build -- the output and the figure below are what the engine actually produced. Simplest first.

img = load_image("sample.bmp")
rotated = imrotate(img, 45, method="bilinear", bbox="loose")
imshow(rotated)

from images

img = load_image("sample.bmp")
edges = edge_detect(grayscale(img))
imshow(edges)

from images

img = load_image("sample.bmp")

# Rotate 30 degrees about the origin, then shift right/down by (50, 20).

M = affine_translate(50, 20) * affine_rotate(30)
out = imwarp(img, M, method="bilinear", bbox="loose", fill=255)
imshow(out)

from images

# A gradient with a bright bar in it, so the rotation below is visible:

# a symmetric test image would look identical afterwards.

n = 48
g = zeros(n, n)
for i in 0 to n - 1
    for j in 0 to n - 1
        g[i, j] = 40 + 3 * j
        if i > 10 and i < 22 and j > 6 and j < 30
            g[i, j] = 240
        end if
    end for
end for
save_image("sample.bmp", image_from_matrix(g))

img = load_image("sample.bmp")
gray = grayscale(img)
imshow(gray)

from images

How it works

load_image(path) — PNG, BMP, JPEG and TIFF (see the image module doc for the pixel/file-format decisions: PNG and BMP are hand-rolled there on top of the existing DEFLATE code, JPEG and "clear error on a bad path/file" convention as read_csv/write_csv.

From the note above this builtin in the interpreter, where the reasoning was written down as it was built.