LuaQOI

Lua libary for decoding an encoding .qoi images on a similar level to FFMPEG/GIMP/IM.

Decoder arguments:

qoid.decode(data_source,[no_alpha]) -> [table]

• data_source[table] list in some way representing data given to the decoder, can have 3 entries
  • data: raw binary string of image data
  • file: path to an image file
  • handle: binary file handle (QOI_D closes this handle)
• no_alpha[boolean]: if an image has an alpha channel, this strips it (useful for easier handling of hexadecimal output data), defaults to false

Decoder result [table]

• width[u32]: Width of the decoded image
• height[u32]: Height of the decoded image
• pixels[table]: 2D array[y][x] storing all the pixel colors encoded as hex
• channels[string]: Either "RGB" or "RGBA"
• colorspace[string]: Either "SRGB_LINEAR_ALPHA" or "SRGB_LINEAR"

---

Encoder arguments:

qoie.encode(image_data,[width],[height],[alpha_channel],[output_file],[colorspace]) -> [string]

• image_data[table]: 2D array[y][x] containing all the pixels we want to encode into the QOI (either as hex or 3/4 entry tables, 4 entries used for alpha/transparency)
• width[u32]: Desired width of the encoded image, defaults to the length of the first image row (#image_data[1])
• height[u32]: Desired height of the encoded image, defualts to the row count of image_data (#image_data)
• alpha_channel[boolean]: Enables alpha channel encoding on the image, hex format: 0xRRGGBBAA, defaults to false
• output_file[string]: Automatically saves the resulting binary string to a file given a path, defaults to no file saving.
• colorspace[string]: QOI image colorspace, defaults to SRGB_LINEAR_ALPHA.

Encoder result [string]

• A binary string containing all of the image data, can be saved to a file via binary file handle.

Example decoder usage:

local img_src = select(1,...)
local pixel_x = tonumber(select(2,...))
local pixel_y = tonumber(select(3,...))

local qoid = require("qoi_d")

local decoded = qoid.decode({file=img_src})

local color_hex = decoded.pixels[pixel_y][pixel_x]

print(("Pixel at %s:%s is #%x"):format(
    pixel_x,pixel_y,
    color_hex
))

Example encoder usage

local qoie = require("qoi_e")

local data = {
    {0xFF0000,0x0000FF},
    {0x00FFFF,0xFFFF00}
}

local dat = qoie.encode(data)

or something like this

local qoie = require("qoi_e")

local data = {
    {0xFF0000,0x0000FF},
    {0x00FFFF,0xFFFF00},
    {0x0000FF,0xFF0000}
}

qoie.encode(data,2,3,false,"epic_output.ppm")