APL (Dyalog Unicode), 11 bytes^SBCS

Full program. Prints 448-by-448-by-4 array representing a 448-by-448 rgba image.

448 448 4⍴0

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⍴ is reshape

Processing, 66 bytes

PGraphics g=createGraphics(448,448);g.beginDraw();g.save("a.png");

Imagemagick in some shell, 35

convert -size 448x448 xc:none a.png

Is this allowed?

Python 2.7, 17 Bytes (22 With Print)

[[[0]*4]*488]*488

With Print:

print[[[0]*4]*488]*488

As variable:

x=[[[0]*4]*488]*488

As an array of RGBA is allowed, that is what I have created above, defaulting to all 0's - meaning black, but totally transparent.

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Jelly, 8 bytes

448ṁ4¬¥þ

A niladic Link which yields a 448 by 448 RGBA array of transparent black pixels.

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How?

448ṁ4¬¥þ - Link: no arguments

448      - 448

       þ - outer-product with: -- i.e. [[f(x,y) for y in [1..448]] for x in [1..448]]

      ¥  -   last two links as a dyad:

   ṁ4    -     mould like [1,2,3,4]  -- e.g. x=7 -> [7,7,7,7]

     ¬   -     logical NOT                       -> [0,0,0,0]

Jelly, 10 9 bytes

x4Wẋ448Ɗ⁺

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Outputs a 448x448x4 array

Thanks to @JonathanAllan for saving a byte.

Go, 70

import i"image";func a()i.Image{return i.NewRGBA(i.Rect(0,0,448,448))}

Never seen a golf in Go before. Defines a function called a that outputs the image

C# (Visual C# Interactive Compiler), 48 bytes

_=>(Enumerable.Repeat((0,0,0,0),200704),448,448)

Apparently outputting [1D array of pixels, width, height] is ok, so this outputs a tuple of `(IEnumerable of pixels, width, height).

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C# (Visual C# Interactive Compiler), 58 bytes

_=>Enumerable.Repeat(Enumerable.Repeat((0,0,0,0),448),448)

The original matrix returning answer.

Since the image IO rules allow output as a matrix of RGB values, this submission outputs a matrix of RGBA values, represented by tuples with four values, all being 0.

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dzaima/APL + APLP5, 18 bytes

{P5.img 448 448⍴0}

Function that outputs an image object that can be drawn to the screen (for no effect) or converted back to pixel values.

Java 8

Saving the image to a file with path s, 101 bytes

s->javax.imageio.ImageIO.write(new java.awt.image.BufferedImage(448,448,2),"png",new java.io.File(s))

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Returning the BufferedImage, 47 bytes

()->new java.awt.image.BufferedImage(448,448,2)

Saving the image to the file f, 83 bytes

f->javax.imageio.ImageIO.write(new java.awt.image.BufferedImage(448,448,2),"png",f)

Dumping PNG to STDOUT, 93 bytes (thanks ASCII-only!)

()->javax.imageio.ImageIO.write(new java.awt.image.BufferedImage(448,448,2),"png",System.out)

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JavaScript (Node.js), 42 bytes

_=>[Array(200704).fill([0,0,0,0]),448,448]

Apparently outputting [1D array of pixels, width, height] is ok.

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HTML, 25 bytes

Is this valid?

<svg height=448 width=448

Test it (background applied with CSS so you can "see" it)

JavaScript (ES6), 74 69 bytes

f=

(_=document.createElement`canvas`)=>_.toDataURL(_.height=_.width=448)

;document.write(f());

Returns a PNG image encoded as a data: URL suitable e.g. for setting as the src of an HTMLImageElement. Edit: Saved 3 bytes thanks to @Shaggy and a further 2 bytes thanks to @Arnauld.

SmileBASIC, 27 bytes

DIM A[448,448]SAVE"DAT:I",A

Saves a 2-dimensional 448x448 array filled with 0s to a file named DAT:I

Rust - 206 201 bytes

use std::{fs::File,io::Write};fn main(){File::create("o.tga").unwrap().write(&vec![0,0,2,0,0,0,0,0,0,0,0,0,192,1,192,1,32,0].iter().chain(vec![0u8;802816].iter()).map(|n|*n).collect::<Vec<u8>>());}

This write an actual, readable .tga file, per http://paulbourke.net/dataformats/tga/ by hard coding the width,height, into the binary file header.

-5 bytes shorten filename, fix img size, @ASCII-only

Jstx, 24 bytes

♪☺ü@/øP♦£Q)%)£Q◄úæD)%)£Q

Explanation

♪☺ü@ # Push literal 448

/    # Store the first stack value in the a register.

ø    # Push literal 0

P    # Push four copies of the first stack value.

♦    # Push literal 4

£Q   # Push stack values into a list of the size of the first stack value starting with the second stack value.

)    # Push the value contained in the a register.

%    # Push the second stack value the absolute value of the first stack value times.

)    # Push the value contained in the a register.

£Q   # Push stack values into a list of the size of the first stack value starting with the second stack value.

◄úæ  # Push literal n

D    # Push the sum of the second and first stack values.

)    # Push the value contained in the a register.

%    # Push the second stack value the absolute value of the first stack value times.

)    # Push the value contained in the a register.

£Q   # Push stack values into a list of the size of the first stack value starting with the second stack value.

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