it's plain to see.
an example, a picture you have posted, it is 88 kB in size.
if you check this your post's transaction on-chain ( in the top left menu of any post ), you can see the tx size is 976 bytes and your image data is not there, only your text.
What the chain says
- Block
- 691 476
- Time
- 2021-06-13T13:33:30Z
- Signer
- 18GVc5vz7teAeKh18Mr7af1SQ13ddm2Max
- App
- twetch
- Type
- post
- Content type
- text/plain
Fields the transaction did not carry are omitted. Open the payload to see the bytes as stored.
Signed by
18GVc5vz7teAeKh18Mr7af1SQ13ddm2Max Verified