Re: paleonet Digital Images & PaleoBase

[TomDeVrie@xxxxxxx]

Here are some detailed steps for merging digital images in Photoshop.  If 
you're working with objects that have relatively simple topologies, like most 
clams and many snails, its easy to encompass portions that are in and out of 
focus. 

To produce a composite image:


1. Take two digital images at different depths-of-field that also overlap in 
their depth-of-focus range;


2. open both in Photoshop;

NOTE:  With a 3.4 megapixel camera, which will produce about 600 pixels per 
linear inch for a 3-inch photo, you'll be working with two 9 megabyte files.  
Thus, you'll need to have enough RAM and hard drive space for Photoshop to 
open these images simultaneously and juggle a few scratch files, as well.


3. Re-size one photo to match the other (there is usually a 0.5% difference 
in size that should be fixed). Recent versions of Photoshop have a measuring 
tool that can be used to calculate the distance from one point to another on 
an image.  Images can be re-sized from the menu bar.


4. Drag one image onto the other to create a new document with two layers;


5. Set one layer (image) to "screen" mode;


6. Align the two images at high magnification as best as possible;


7. Outline and delete the out-of-focus portion of one layer;


8. Go to the other layer and outline and cut a complementary out-of-focus 
portion of this other layer. Be sure not to overlap the deletions; you can 
keep track easily of what's been cut by the darkness of the images: 
bright=cut at one layer or the other; dark=uncut overlap, presumably in focus 
for both images; white=oops! - deletions overlapped).


9. Set the "screen" layer to "dissolve;"


10.  "Flatten" the image.


11. Save document.  Once flattened (but not before), it can be saved as a 
generic tiff or jpg file as well as a Photoshop file.


If you have a complex topology, this method would be more difficult and time 
consuming; some computerized process might be needed.


Tom DeVries