the feed/api for each photo contains 3 thumbs and a large picture which are accessible on the native http rest api in the following:
"media$thumbnail":[
{
"url":"https://lh3.googleusercontent.com/-_FFMNGPU1TQ/TtukXyN4eCI/AAAAAAAACso/EzPmut2iKVQ/s72/DSC01612.JPG",
"height":72,
"width":48
},
{
"url":"https://lh3.googleusercontent.com/-_FFMNGPU1TQ/TtukXyN4eCI/AAAAAAAACso/EzPmut2iKVQ/s144/DSC01612.JPG",
"height":144,
"width":96
},
{
"url":"https://lh3.googleusercontent.com/-_FFMNGPU1TQ/TtukXyN4eCI/AAAAAAAACso/EzPmut2iKVQ/s288/DSC01612.JPG",
"height":288,
"width":192
}
],
LARGE ONE:
"media$group":{
"media$content":[
{
"url":"https://lh3.googleusercontent.com/-_FFMNGPU1TQ/TtukXyN4eCI/AAAAAAAACso/EzPmut2iKVQ/DSC01612.JPG",
"height":512,
"width":341,
"type":"image/jpeg",
"medium":"image"
}
similar reference
When coding clients to an underlying REST api it can often help to have a good grasp on the native protocol and what character streams ( request / response ) are on the wire. Then you adapt PHP/Curl to what is there in http protocol.
The google oauth playground is a great tool for testing the back and forth dialogs involved in development against any of the gdata apis ( including picasa )...
playground
here is the playground request code to get the thumbs and the large pic for a given album/photo...
GET //data/entry/api/user/rowntreerob/albumid/5682316071017984417/photoid/5682316083381958690?fields=media%3Agroup%2Fmedia%3Athumbnail%5B%40url%5D%2Cmedia%3Agroup%2Fmedia%3Acontent%5B%40url%5D&alt=json HTTP/1.1
Host: picasaweb.google.com
Authorization: OAuth ya29.AHES6ZT123y3Y5Cy3rILYg4Ah4q....
HTTP/1.1 200 OK
status: 200
gdata-version: 1.0
content-length: 756
x-xss-protection: 1; mode=block
content-location: https://picasaweb.google.com//data/entry/api/user/rowntreerob/albumid/5682316071017984417/photoid/5682316083381958690?fields=media%3Agroup%2Fmedia%3Athumbnail%5B%40url%5D%2Cmedia%3Agroup%2Fmedia%3Acontent%5B%40url%5D&alt=json
x-content-type-options: nosniff
set-cookie: _rtok=a1p2m3PiHFkc; Path=/; Secure; HttpOnly, S=photos_html=sX3EHuLxGEre_OMvR0LTPg; Domain=.google.com; Path=/; Secure; HttpOnly
expires: Wed, 16 May 2012 03:23:51 GMT
vary: Accept, X-GData-Authorization, GData-Version, Cookie
x-google-cache-control: remote-fetch
-content-encoding: gzip
server: GSE
last-modified: Fri, 06 Jan 2012 17:57:33 GMT
via: HTTP/1.1 GWA
cache-control: private, max-age=0, must-revalidate, no-transform
date: Wed, 16 May 2012 03:23:51 GMT
access-control-allow-origin: *
content-type: application/json; charset=UTF-8
x-frame-options: SAMEORIGIN
and the response to the above run thru a prettyprint...
"version":"1.0",
"encoding":"UTF-8",
"entry":{
"xmlns":"http://www.w3.org/2005/Atom",
"xmlns$media":"http://search.yahoo.com/mrss/",
"media$group":{
"media$content":[
{
"url":"https://lh3.googleusercontent.com/-_FFMNGPU1TQ/TtukXyN4eCI/AAAAAAAACso/EzPmut2iKVQ/DSC01612.JPG",
"height":512,
"width":341,
"type":"image/jpeg",
"medium":"image"
}
],
"media$thumbnail":[
{
"url":"https://lh3.googleusercontent.com/-_FFMNGPU1TQ/TtukXyN4eCI/AAAAAAAACso/EzPmut2iKVQ/s72/DSC01612.JPG",
"height":72,
"width":48
},
{
"url":"https://lh3.googleusercontent.com/-_FFMNGPU1TQ/TtukXyN4eCI/AAAAAAAACso/EzPmut2iKVQ/s144/DSC01612.JPG",
"height":144,
"width":96
},
{
"url":"https://lh3.googleusercontent.com/-_FFMNGPU1TQ/TtukXyN4eCI/AAAAAAAACso/EzPmut2iKVQ/s288/DSC01612.JPG",
"height":288,
"width":192