# (merging previous post)
my @sorted_indices = sort {$a <=> $b} keys %upload;
my %lookup_hash;
@lookup_hash{@sorted_indices} = 0 .. $#sorted_indices;

##</code><code>##

my $i = $lookup_hash{5};
print $x,"\n"; # prints 2

# get the next element from the hash
my $next = $sorted_indices[$x + 1]; # $next holds 7

# get your image
my $image = $uploads{$next};