Why iMessage can't sand pictures SMS.

You use three conflicting terms.

• "iMessage" means messages sent to or from Apple devices.
• "SMS", meaning short message service, is a cellular text message sent over your cellular carrier's network. SMS only sends/receives simple text messages.
• "Pictures" can only be messaged using iMessage (to/from other Apple devices), or MMS, meaning multimedia message service, over your cellular carrier's network. MMS capability on your plan often costs extra from your cellular carrier.

There'ss actually no such thing as a picture SMS as SMS is purely text only. An MMS message can include images or video. To send MMS, assuming your carrier and your plan provides for it, requires you to have cellular data turned in.

Do you have cellular data on? If so, does your cell service plan provide for MMS?