Hi Asael,
Are you doing a right-click on the image and then pressing Save As?
If so, there’s indeed another way that will only save the actual image. This is done by opening the settings of Image Simulation, pressing the Settings test on the top-left corner of the window, and type an Output File. This is an excerpt from the Help File:
Output File If a file name ending in the BMP, JPG, or PNG extension is provided, then the simulated image will be saved in the specified file and be placed in the <images> folder (see “Folders”).
By default this folder is located under {Your Documents}\Zemax\IMAFiles, and should have the same size as the bitmap as long as you did not oversampled, use a guard band, or change the X/Y Pixels value.
Take care,
David