How to carry out enumeration?

Question

bash

#!/bin/bash
echo "Start"
for file in `find test/*/*.png`
do
  convert $file $file.gif
done
echo "Finish"

Such a script does an action in each of the test subdirectory: it converts each png file into a new gif file. Is it possible to combine all the files in a subdirectory into one and move on to the next folder?
The output will be as many new files as there are folders, not as many old png files.
Thank you all and I apologize for the stupidity of the question)

Answer 1

$ find ./test -type f -name '*.png' -exec convert {} {}.gif \;

Do you need to concatenate files or what?

#!/bin/bash
set -e
for dirs in $(find ./test -type d -name 'images'); do
  for dir in "${dirs}"; do
    imgs=$(find "${dir}" -type f -name '*.jpg' -o -name '*.jpeg' -o -name '*.png')
    cat ${imgs} > "${dir}"/$$.gif;
  done
done

./test
├── 1
│   └── images
│       ├── 1.jpg
│       ├── 2.jpg
│       ├── 3.jpg
│       └── 4898.gif
├── 2
│   └── images
│       ├── 1.jpg
│       ├── 2.jpg
│       ├── 3.jpg
│       └── 4898.gif
├── 3
│   └── images
│       ├── 1.jpg
│       ├── 2.jpg
│       ├── 3.jpg
│       └── 4898.gif
└── images
    ├── 1.jpg
    ├── 2.jpg
    ├── 3.jpg
    └── 4898.gif

Answer 2

How to reduce thousands of pictures in all subfolders?