If you are using Windows, try opening the picture in whichever program you normally open pictures with. Then use the Windows snipping tool (usually located in the Windows accessories folder) then basically do a screen capture of the picture with the Snipping Tool. This usually decreases the size of the file substantially.
Just an FYI before you spend a lot of money. I saw some news about Visas in Thailand yesterday (article below) and they said that elite visa holders have been allowed to return to TL since August, but because of the bureaucracy, only 50 of them have been successful in returning.
