Sorting in Power View
In a Power View sheet, you can sort data in tables, matrices, and bar and column charts. You can sort individual charts within multiples. You can sort numeric fields, such as Sales Amount, and non-numeric fields, such as Name.
Sort images in Power View
Power View cannot sort binary values like photos. Therefore it sorts by another column—which column is determined by settings in the model on which the report is based.
If the Sort by Other Column property is set, then Power View sorts by that column.
If not, but the table has a Default Label column set, then Power View sorts by that column.
If neither, then the image sorts by the Row ID field.
More about sorting images in Power View.