I don't know much about PNG files, but the smallest PNG file I was able to make was 127 bytes. That's a 1x1 pixel image. On the other hand, if your perl script responded with a 1x1 GIF image, it would only be 35 bytes. Much smaller! I can show you how to do that. I have to admit, I copied this code from someone else on here. lol :D
#!/usr/bin/perl
use strict;
use warnings;
SpitGIF();
exit;
##################################################
# GIF | Graphics | v2023.2.5
# This function generates a single-pixel GIF of a given color
# I took original code from PerlMonks and modified it a little bit.
# Original code was written by a user named "turnstep"
# and is called the World's Smallest GIF image. It produces a GIF
# image that is only 35 bytes (or 43 bytes if it is transparent.)
# Source: https://perlmonks.com/?node_id=7974
#
# This function expects one or two arguments. The first argument
# should be a hexadecimal number such as 0xCC00CC which would
# produce a purple pixel.
#
# Note: This function will always generate the smallest possible
# GIF image. If you would like to generate a 1x1 BMP image,
# use the SpitBMP() function.
#
# Examples:
#
# SpitGIF() will send a black 1x1 pixel to the browser.
#
# SpitGIF(0xFFFFFF) will send a white 1x1 pixel to the browser
# as response by printing it to stdout.
#
# SpitGIF(-1) will send a transparent pixel to the browser.
#
# The following example will simply return a grey 1x1 GIF
# file's content in a string rather than printing it:
#
# my $GIF = SpitGIF(0x999999, '<STRING>');
#
# Next example will save a red GIF pixel to a file called "red.gif"
#
# SpitGIF(0xFF0000, 'red.gif');
#
# The next example will return a base64 inline code that can be
# inserted into a HTML page and will produce a green GIF pixel:
#
# my $GIF = SpitGIF(0x00FF00, '<INLINE>');
# print "<IMG WIDTH=1 HEIGHT=1 BORDER=0 SRC='$GIF'>";
# ^ Here the $GIF
# variable contains the GIF file's contents in base64 encoding
# rather than a gif file name. Newer web browsers will recognize
# this and will render the image correctly. Very old web browsers
# such as MSIE6 will just display a missing image icon.
#
# Usage: SpitGIF(COLOR, [OUTPUT])
#
sub SpitGIF
{
my $COLOR = defined $_[0] ? $_[0] : 0;
my $GHOST = ($COLOR & 0xFF000000) ? "!\xF9\4\5\x10\0\0\0" : '';
$COLOR = substr(pack('N', $COLOR & 0xffffff), 1, 3);
# Create the world's smallest GIF image:
my $GIF = "GIF89a\1\0\1\0\x90\0\0$COLOR" .
"\0\0\0$GHOST,\0\0\0\0\1\0\1\0\0\2\2\4\1\0;";
# If $_[1] is not empty, then...
unless (defined $_[1] && length($_[1]) && $_[1] =~ m/\S+/)
{
binmode(STDOUT);
return print "Content-Type: image/gif\nContent-Length: ",
length($GIF), "\n\n", $GIF;
}
my $F = $_[1];
if ($F eq '<STRING>') { return $GIF; }
if ($F eq '<INLINE>') { EncodeBase64($GIF, 1);
return "data:image/gif;base64,$GIF"; }
print "\nSaving 1x1 GIF image to $F\n";
return CreateFile($F, $GIF);
}
##################################################
# String | v2022.11.4
# This function converts a string to text using the
# standard Base64 encoding algorithm.
#
# THIS FUNCTION CHANGES THE VALUE OF THE FIRST ARGUMENT!
#
# The first argument should be a string or a string reference.
# The second argument MAY contain a custom 65-byte
# character set. The 65th byte will be used for padding.
#
# The second argument MAY also be 0 or 1:
# 0 = Use standard Base64 encoding which ends with +/ (default)
# 1 = Use web-safe Base64 encoding which ends with -_
#
# Usage: EncodeBase64(STRING, [CHARSET])
#
sub EncodeBase64
{
defined $_[0] or return $_[0] = '';
# Prepare character set.
my $PADDING = '=';
my $BASE64 = defined $_[1] ? $_[1] : 0;
if (length($BASE64) >= 64)
{ $PADDING = substr($BASE64, 64, 1); }
else { $BASE64 =
'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789'
. (($BASE64 eq '1') ? '-_' : '+/'); }
# Get string reference.
my $REF = ref($_[0]);
if (length($REF))
{
$REF eq 'SCALAR' or return 0;
$REF = $_[0];
defined $$REF or return $$REF = '';
}
else { $REF = \$_[0]; }
my ($i, $OUT, $L) = (0, '', length($$REF));
while ($i < $L)
{
# Read 3 bytes.
my $A = vec($$REF, $i++, 8);
my $B = vec($$REF, $i++, 8);
my $C = vec($$REF, $i++, 8);
# Write 4 bytes.
$OUT .= substr($BASE64, $A >> 2, 1);
$OUT .= substr($BASE64, (($A & 3) << 4) | ($B >> 4), 1);
$OUT .= substr($BASE64, (($B & 15) << 2) | (($C >> 6) & 3), 1);
$OUT .= substr($BASE64, $C & 63, 1);
}
# Replace last couple of bytes with padding.
my $DIFF = $i - $L;
substr($OUT, length($OUT) - $DIFF, $DIFF) = $PADDING x $DIFF;
$$REF = $OUT; # Replace original string with the new one.
undef $OUT; # Free up memory.
return 1;
}
##################################################
# File | v2022.11.8
# Creates and overwrites a file in binary mode.
# If the file has already existed, it erases the
# old content and replaces it with the new content.
# Returns 1 on success or 0 if something went wrong.
#
# Usage: STATUS = CreateFile(FILENAME, CONTENT)
#
sub CreateFile
{
my $F = defined $_[0] ? shift : '';
$F =~ tr`<>*%$?\x00-\x1F\"\|``d; # Remove illegal characters.
local *FILE;
open(FILE, ">$F") or return 0;
binmode FILE;
foreach (@_) { defined $_ and length($_) and print FILE $_; }
close FILE;
-e $F or return 0; # File exists?
-f $F or return 0; # It's a plain file?
return 1;
}
##################################################
# BMP | v2022.10.11
# This function returns a 1x1 truecolor BMP image
# with a Version 40 header which is considered standard.
# All photo editors and web browsers should be able
# to open this type of file with no problem.
# (The entire BMP image is 58 bytes long.)
#
# The first argument (RGBColor) should be a 32-bit integer
# which holds the R-G-B values in the following order: 0x00rrggbb
#
# Usage: STRING = SpitBMPv40(RGBColor)
#
# Example: SpitBMPv40(0xff0000) -- returns a red pixel
# SpitBMPv40(0x00ff00) -- returns a green pixel
# SpitBMPv40(0x0000ff) -- returns a blue pixel
#
sub SpitBMPv40
{
my $PIXEL = defined $_[0] ? $_[0] & 0xffffff : 0;
####################################################################
+############################
# v40 Standard Windows BMP Structure
#
# BMP Version Bits Per Pixel
+ Number of Colors Used (0=All)
# Header Length \ Width | Compressi
+on / Important Colors (0=All)
# File Size \ \ \ Height | / DataSiz
+e / /
# \ \ \ \ \ | / /
+ / /
return 'BM' . pack('V6vvV7', 58, 0, 54, 40, 1, 1, 1, 24, 0, 4, 0, 0,
+ 0, 0, $PIXEL);
# | | | \/
# File Signature Reserved Planes Recommen
+ded Horizontal & Vertical Density for Printing
}
##################################################