Multiple images added to ArcMap data view appear with a white gap between them.
The default resampling method for image display is inappropriate for the image type.
Solution or Workaround
Follow the solution below.
Change the display resampling method from Bilinear Interpolation to Nearest Neighbor.
A. Right-click image layer in ArcMap Table of Contents.
B. Click Properties.
C. Click Display tab.
D. Change 'Resample during display using' from Bilinear Interpolation to Nearest Neighbor or 'Other'.
E. Click Apply.
F. Click OK.