This is the NTA rule regarding Postcard photo size:

• Uploading of Post Card size photograph: Instructions:

Must be latest post card size picture in a white background with the Name of the candidate and date written on the photograph. The Size must be 10 Kb to 100 Kb and format should be JPG. Please follow this instruction.

• Uploading of Photograph: Instructions
  
  Must be latest passport picture in a white background with the Name of the candidate and date written on the photograph. The Size must be 50 Kb to 300 Kb and format should be JPG. The focus has to be on the face with 80% coverage and ears clearly visible.
• Uploading of Signature: Instructions

Candidates must sign with a black pen on a white background in JPG format with a file size of 4 Kb to 30 Kb

• Uploading of Left hand thumb impression: Instructions:

The file size should be 10kb-50kb in JPG/JPEG format.

• Class 10th Passing certificate: Instructions:

File size of 100kb to 400 kb in JPG/JPEG format.