Best way to combine 8-bit and 16-bit image files?

Question

I produce large photographic art prints by combining my own edited 16-bit RAW photo images with 8-bit stock photo images and 8-bit photoshop artwork. I used to just reduce my 16-bit photos to 8-bit and then edit my composite image as 8-bit, but I ran into banding and other problems in the color gradients I created later in my composite image.
I want my composite image to be 16-bit to get more accurate colors and better gradients. What is the best way to bring 8-bit image files into my composition and maintain best quality? Is it good to convert 8-bit images to 16-bit in PS before importing? I also heard about bringing 8-bit images in as Smart Objects? Thanks for any help on this.

Answer 1

*Photonic wrote:
Thanks Jack and Noel. My workflow usually starts w. a 16-bit RAW image brought into Photoshop as the background layer of the master file. Color space is AdobeRGB. Then 8-bit stock photo and art elements (objects) are brought in by dragging the open 8-bit image up to the master image file tab, and then dropping it back into the image window after the file opens.
Should I use the "Paste In" command instead? I usually avoid copy/paste since some of my element files are usually over 100MB and that seems to challenge my Mac after a while.
Could I convert the 8-bit image files prior to import, like Noel suggests (Image>Mode>16bits)?  Thanks.
There is no need to convert 8bit open documents to 16bit mode Photoshop will convert the copied layers to 16bit bit during the drag copy.  Converting the open document would just increase Photoshop RAM usage every layer pixels bytes used  would double in size.
If you element files are over 100MB they are most likely layered files.  If all you need is a composite you should avoid using Place for that will needlessly inflate your document size. Instead open the element file create a new layer that is a stamp visible layer (Shift+Alt|Opt+Ctrl|Cmd+E) and drag that layer to you document then close nosave your element file. Copy only copies the targeted layer or there is a Copy Merge that copies the composit merge of all targeted layers. It a bit hard to create an action that would be able to use Copy or Copy Merge. Using the above stamp visible way can be made into an action. You also do not want to drag all the layers to your document if you just need a composit layer.
You could also automate the element file copy with an action.
Action Step 1 Insert menu into File>Open this will be an interactive step you must select a file to open. When the action is played.
Step 2 (Shift+Alt|Opt+Ctrl|Cmd+N) Create a new empty layer This will always work
Step 3 (Shift+Alt|Opt+Ctrl|Cmd+E) stamp visible layers into the new layer
Step 4 (Ctrl|Cmd+A) select all
Step 5 (Ctrl|Cmd+C) Copy
Step 6 Close current document no save
Step 7 (Ctrl|Cmd+P) Paste into the document your working on Photoshop will convert to 16bit if the document is 16bit mode and the clipboard content is 8bit.
When you use Photoshop and do something.  Think to yourself how did Photoshop do what you asked it to do. Thing about what is involved what layers must be used etc. How is the feature/function done.
Message was edited by: JJMack
Message was edited by: JJMack