Does it cost to send picture messages on imessage to another iphone with imessage?

iMessage does not use your vendor's text messaging so it won't take away from that. However, if on 3G is does use data so will take from whatever plan you have for data. If over WiFi at home then will use data from any home plan - if in a public WiFi spot then not your data either. Any message is a very small user of data.

So a long answer - it really depends upon where and the details of your data plan but it doesn't use your vendor text message allocation

I just found out that sending pix is not free over 3G. I saw charges on my phone bill and called Verizon. I was then referred to Apple Care. After talking to Apple, found out that MMS is only free if sent over WiFi even if through IMessage. Your carrier will charge your MMS charges even if it is with IMessage.

Sending an iMessage MMS is "free" in that you pay for the data if using 3G. If only on Wi-Fi you can do it for free.

FaceTime is free but for right now requires a Wi-Fi connection unless you JB.

I can’t send pictures via wifi network but I could with my data ? why so ?

Not true. Sprint counts iMessages as text messages. I called them and they confirmed it. They also made it clear that it wasn't going towards the data plan but towards the actual text message plan.