Qrecreate

The challenge provides 100 directories, each containing a data/img.png file. The directory names look like Base64-encoded values, so the first step is to decode them. Once decoded, they map cleanly to values from 001 to 100, which gives the correct order of the image fragments. I then copied each img.png out of its directory and renamed it with its decoded numeric values.

for dir in [0-9]*/; do                          venv 3.14.3  05:51 
    cp "$dir/data/img.png" "${dir%/}.png"
done

Each fragment is 74x74 pixels, and there are 100 fragments in total, which strongly suggests a 10x10 layout. I wrote a short Python script with PIL to rebuild the full image by placing the tiles in order from 001 to 100, row by row. This produced a final 740x740 image called output.png.

from PIL import Image
import os

##  Grid 10X10, each size is 74X74, so final image size of 740x740 ?

## To remap each square into the grid,
# Check in which row to place it, Value // 10
# Check in which col to place it, Value % 10

Result = Image.new("RGB", (740, 740)) ## Create blank image.
getdirs = os.listdir()
dic = {}
for dir in getdirs:
    if ".png" not in dir:
        continue
    pos = int(dir.strip("qr_").strip(".png"))
    dic[pos] = dir

for i in range(1 ,101):
    y = (i - 1) // 10
    x = (i - 1) % 10

    Tmp = Image.open(f"./{dic[i]}")
    Result.paste(Tmp, (x*74, y*74))
    
Result.show()
Result.save("output.png")

The reconstructed image is a QR code. Reading it with zbarimg output.png returns a long Lorem Ipsum text, but the important part is the suspicious Base64 string embedded in that output. Extracting that Base64 value and decoding it reveals the flag.