Overlaying images with Photoshop

Applying Scale Bars

1. Open the tif image to add the scale bar to
   
   
2. Check to see if it is RGB ( Image menu, Mode, RGB; )
   
   
3. Open the appropriate scale bar image tif (see Scale Bars to download tif)
   
   
4. Change it to RGB -choose Image menu, Mode, RGB;
   
   
5. Choose the arrow with the cross from the left hand tool bar (Move Tool):
   
   
   
   
6. Drag anywhere in the scale bar onto the image to add the scale bar to then position as you wish. Scale the whole picture from here on and the scale bars will remain true.

Note: when saved as a tif from here the scale bar will be flattened onto the image and cannot be moved again. If you think you may want to re-position it, keep a copy of the overlayed file in Photoshop format (.psd)

Overlaying 2 or more coloured images

1. If you have already converted your grayscale images (see Colouring those Greyscales) then choose Image menu, Mode, RGB; otherwise open the two or more TIF files you wish to overlay and choose Image menu, Mode, RGB for each.
   
   
2. Now choose Image menu, Apply Image... to bring up the following Dialog:
   
   
   
   
3. Click & hold down down Source option then select the image name you wish to apply. Click on OK.
   
   
4. Under Target, set Blending to Screen, then click OK
   
   
5. To apply a third picture open the picture first then click back to the double overlayed picture to make it active then repeat from step 2.