Thanks for reporting your issue. Please make sure these boxes are checked before submitting your issue - thank you!

- [x] I looked for a similar issue and couldn't find any.
- [x] I tried with the latest version of GPAC. Installers available at https://gpac.io/downloads/gpac-nightly-builds/
- [x] I give enough information for contributors to reproduce my issue (meaningful title, github labels, platform and compiler, command-line ...). I can share files anonymously with this dropbox: https://www.mediafire.com/filedrop/filedrop_hosted.php?drop=eec9e058a9486fe4e99c33021481d9e1826ca9dbc242a6cfaab0fe95da5e5d95

Detailed guidelines: https://gpac.io/bug-reporting/

## Overview

Generating single channel files (e.g. palette or mono) results in corrupted results in gpac -gui for row and tile interleave mode.

## Test cases:
```
gpac uncvg:sq=1:vsize=30x20:tiles=2x4:c=M:sampling=none:interleave=row:block_size=0:row_align=0:tile_align=0:fps=0 -o test1.heif
gpac uncvg:sq=1:vsize=30x20:tiles=2x4:c=M:sampling=none:interleave=tile:block_size=0:row_align=0:tile_align=0:fps=0 -o test2.heif
gpac uncvg:sq=1:vsize=30x20:tiles=2x4:c=p:sampling=none:interleave=row:block_size=0:row_align=0:tile_align=0:fps=0 -o test3.heif
gpac uncvg:sq=1:vsize=30x20:tiles=2x4:c=p:sampling=none:interleave=tile:block_size=0:row_align=0:tile_align=0:fps=0 -o test4.heif
gpac uncvg:sq=1:vsize=30x20:c=M:sampling=none:interleave=row:block_size=0:row_align=0:tile_align=0:fps=0 -o test5.heif
gpac uncvg:sq=1:vsize=30x20:c=p:sampling=none:interleave=row:block_size=0:row_align=0:tile_align=0:fps=0 -o test6.heif
gpac uncvg:sq=1:vsize=30x20:c=x,M:sampling=none:interleave=row:block_size=0:row_align=0:tile_align=0:fps=0 -o test7.heif
```

## Results

Test 1
![image](https://github.com/gpac/gpac/assets/174642/9f1341fc-f4e9-40e3-b48a-a554f314be74)

Test 2
![image](https://github.com/gpac/gpac/assets/174642/dc2a835c-2afa-4dd1-83ce-998fa1abd65c)

Test 3
![image](https://github.com/gpac/gpac/assets/174642/5a9abe65-4a02-4824-bd6b-53facaf4868c)

Test 4
![image](https://github.com/gpac/gpac/assets/174642/7b8f04b7-4a13-465e-8270-484ef7e95b6a)

Test 5
![image](https://github.com/gpac/gpac/assets/174642/e9685b25-9ef0-415d-9d16-ba60b427df9b)

Test 6
![image](https://github.com/gpac/gpac/assets/174642/fe6f5edb-9683-46a5-8a72-4af8e21d146c)

Test 7
![image](https://github.com/gpac/gpac/assets/174642/e1f709cf-ed3e-4431-a78b-0e97bf956a23)

(note: this is the expected result, but differs from Test 5 example only in that there is a pad channel.)
uncompressed generation / decode of single channel images produces corrupted results in row and tile interleave modes
This is a GitHub Issue
repo:gpac
owner:gpac
Title : uncompressed generation / decode of single channel images produces corrupted results in row and tile interleave modes
Issue date:

--- start body ---
Thanks for reporting your issue. Please make sure these boxes are checked before submitting your issue - thank you!

- [x] I looked for a similar issue and couldn't find any.
- [x] I tried with the latest version of GPAC. Installers available at https://gpac.io/downloads/gpac-nightly-builds/
- [x] I give enough information for contributors to reproduce my issue (meaningful title, github labels, platform and compiler, command-line ...). I can share files anonymously with this dropbox: https://www.mediafire.com/filedrop/filedrop_hosted.php?drop=eec9e058a9486fe4e99c33021481d9e1826ca9dbc242a6cfaab0fe95da5e5d95

Detailed guidelines: https://gpac.io/bug-reporting/

## Overview

Generating single channel files (e.g. palette or mono) results in corrupted results in gpac -gui for row and tile interleave mode.

## Test cases:
```
gpac uncvg:sq=1:vsize=30x20:tiles=2x4:c=M:sampling=none:interleave=row:block_size=0:row_align=0:tile_align=0:fps=0 -o test1.heif
gpac uncvg:sq=1:vsize=30x20:tiles=2x4:c=M:sampling=none:interleave=tile:block_size=0:row_align=0:tile_align=0:fps=0 -o test2.heif
gpac uncvg:sq=1:vsize=30x20:tiles=2x4:c=p:sampling=none:interleave=row:block_size=0:row_align=0:tile_align=0:fps=0 -o test3.heif
gpac uncvg:sq=1:vsize=30x20:tiles=2x4:c=p:sampling=none:interleave=tile:block_size=0:row_align=0:tile_align=0:fps=0 -o test4.heif
gpac uncvg:sq=1:vsize=30x20:c=M:sampling=none:interleave=row:block_size=0:row_align=0:tile_align=0:fps=0 -o test5.heif
gpac uncvg:sq=1:vsize=30x20:c=p:sampling=none:interleave=row:block_size=0:row_align=0:tile_align=0:fps=0 -o test6.heif
gpac uncvg:sq=1:vsize=30x20:c=x,M:sampling=none:interleave=row:block_size=0:row_align=0:tile_align=0:fps=0 -o test7.heif
```

## Results

Test 1
![image](https://github.com/gpac/gpac/assets/174642/9f1341fc-f4e9-40e3-b48a-a554f314be74)

Test 2
![image](https://github.com/gpac/gpac/assets/174642/dc2a835c-2afa-4dd1-83ce-998fa1abd65c)

Test 3
![image](https://github.com/gpac/gpac/assets/174642/5a9abe65-4a02-4824-bd6b-53facaf4868c)

Test 4
![image](https://github.com/gpac/gpac/assets/174642/7b8f04b7-4a13-465e-8270-484ef7e95b6a)

Test 5
![image](https://github.com/gpac/gpac/assets/174642/e9685b25-9ef0-415d-9d16-ba60b427df9b)

Test 6
![image](https://github.com/gpac/gpac/assets/174642/fe6f5edb-9683-46a5-8a72-4af8e21d146c)

Test 7
![image](https://github.com/gpac/gpac/assets/174642/e1f709cf-ed3e-4431-a78b-0e97bf956a23)

(note: this is the expected result, but differs from Test 5 example only in that there is a pad channel.)
--- end body ---
