Hi Martin,
Yes if you only want change the size to show the image, you can select the list in the page, then you can go to the Layout tab and select the list into the grid, go to the outline view and open the list, select the blob attribute go to the properties and in the Attr. Layout property select the Layout Parameters(blue button), you can see a popup with the Layout Parameters and you can set the Image width and Image height text fields.
Best regards.