A quick, probably dumb Q about ACR 32 & 64 bit

[AFairley]

I understand that if I open a DNG directly in ACR from Bridge it opens in a 32-bit instance of ACR, but if I open the DNG in PS from Bridge it opens in a 64 bit instance of ACR (on my 64-bit system).  My question is, if I do some edits in 32-bit ACR and then close the file saving the parameters, and then reopen the DNG in 64-bit ACR later for more tweaking, I have not lost any potential quality by working the first time in 32 bit ACR, right?  The 32 vs 64 bit distinction is only important when the parametric edits are actually applied, either in opening in PS as a rasterized image or exporting from ACR to TIFF or JPEG, correct?

As always, thanks!

[Schewe]

No...there is no difference in the settings applied to an image whether ACR is in 32 or 64 bit mode...the "bit" in this case is the application binary and has nothing to do with image "bits".

[AFairley]

the "bit" in this case is the application binary and has nothing to do with image "bits".

Oh right, DOH!  Jeeze, that really was dumb. 

But Jeff, in a previous thread you posted "But if you are opening Camera Raw hosted in Bridge (command/control R) vs Photoshop (command/control O) then you are opening the 32-bit version of Camera Raw, not the 64-bit version. Depending on your Bridge prefs, double-clicking may open ACR hosted in Bridge or in Photoshop. You really, really do want to be sure you open ACR via Photoshop that is running as a 64-bit app, not a 32-bit app."  http://www.luminous-landscape.com/forum/index.php?topic=45590.0

Why is that, is it a refresh speed issue (the topic of the earlier thread) or something else?

Thanks.

[Schewe]

Why is that, is it a refresh speed issue (the topic of the earlier thread) or something else?

Strictly because of the faster speed of opening Camera Raw as a 64-bit plug-in when hosted in Photoshop. Bridge is a 32-bit application and as a result opens the 32-bit version of the plug-in-which will run at less than 64-bit speed & efficiency.

[dmerger]

I'm using CS4 on Windows Vista 64 bit.  I installed just the 64 bit version of CS4.  The only way I found to open a tiff or jpeg in Camera Raw is via Bridge.  Using "Control O" doesn't seem to open Camera Raw for me.  Am I thus limited to just the 32 bit version of Camera Raw?   

[sniper]

ALT+SHIFT+CTRL+O opens the open as window, if you choose camera raw in that you can open a jpeg in ACR that way.

[dmerger]

Thanks, your advice works.  I also discovered that I can open the same "open as" window, giving me the option to open a jpeg or tiff in Camera Raw, as follows:

In PS click on "File", then click on "Show All Menu Items", then click on "Open As". 

Once Camera Raw is open, is there a way to determine whether it is the 64 bit or 32 bit version?

[bjanes]

Strictly because of the faster speed of opening Camera Raw as a 64-bit plug-in when hosted in Photoshop. Bridge is a 32-bit application and as a result opens the 32-bit version of the plug-in-which will run at less than 64-bit speed & efficiency.

According to the Adobe guru, John Nack , the main advantage of 64 bit Photoshop is when one is working with very large files or with many open files when one runs out out of real memory and swapping out to virtual memory is needed. For more modest processing with a few small files, the 32 bit can actually be faster since pointers and op codes are 32 bit rather than 64 bit.

Regards,

Bill Janes

[Schewe]

For more modest processing with a few small files, the 32 bit can actually be faster since pointers and op codes are 32 bit rather than 64 bit.

That's Photoshop not Camera Raw...ACR will be 10-15% faster in 64 bit than 32 bit.