After building and uploading code using WIFI component in SMART mode on ESP32_CAM, try to find it's IP in network.
Then use client.py to download images by this command python client.py -ip <IP> d and if it failed after some while due to wireless disconnections enter python client.py -ip <IP> c to continue downloading.
While ESP32 is on some parameters are adjustable through web server.
FRAMESIZE
From 96x96 to UXGA 1600x1200
PIXFORMAT
JPEG, GRAYSCALE, RGB565 and RAW
PICSPEED
Sample rate 1/2,1/3 and 1/5 per second.
Receive name list of images by:
curl http://<IP>/links > links.txt
Choose your image and download it by:
curl http://<IP>/01000046.jpg > test.jpg