Layers with transparency on a 32-bit .psb?

[aaronpriest]

I'm working with 32-bit .exr source images. PTGui is not blending the sky as well as Photoshop does. Enblend and Smartblend won't work with 32-bit files. I'd like to save out individual HDR layers as 32-bit .psb files to blend in Photoshop but PTGui won't save the layers with alpha channels like it can with 16-bit HDR .psb files. My work around is to save out both and manually load selections on the 32-bit files from alpha channels in the 16-bit files to delete the black areas and then run auto-blend. Incredibly time consuming on a gigapixel image. Too bad Photoshop doesn't support an align to grid feature or I could probably do everything natively in Photoshop, but PTGui is still far better at choosing different projections and especially 360x180 spherical and little planet panoramas. :-)

Any way to get layered support with transparency in 32-bit .psb files?

[PTGui Support]

Hi Aaron,

For the 32 bit psd files generated by PTGui there is an alpha channel
included but Photoshop does not display it by default. You can do this:

- Layers pallette: right click on the Background layer and choose 'Layer
from Background'

- in the Channels pallette: ctrl click on the thumbnail of the 'Alpha 1'
channel. This selects the opaque area of the alpha channel

- Do Select - Inverse

- Select the RGB channel in the Channels pallette

- press the Delete key. This deletes the transparent black area, you now
have proper transparency

Or you can use .exr output from PTGui; be sure to click on Settings and
include the alpha channel. PTGui will warn you that this is not
compatible with Photoshop, but it recent Photoshop versions can read it.

True layered 32 bit output is still on the wish list; in the mean time
see 6.10 for a workaround:
http://www.ptgui.com/support.html#6_10

Joost

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[aaronpriest]

Well, I'm getting somewhere. I created 32-bit .exr files via Photomatix Pro and fed those into PTGui instead of trying to do HDR brackets from 16-bit TIFF files. That seems to be working a lot better with less ghosting so far. I also fed my RAW files into Photomatix Pro instead of TIFFs out of Lightroom and that made a tremendous difference for some strange reason.

At any rate, I've got a nice set of .exr images rendered out of PTGui now (I included the Alpha channels as you suggested) and loading as layers into Photoshop. There is a lot of black area on each file that needs to be selected and deleted, but I do have transparency around the image itself to make this easier. Yay!  Any idea why the black areas aren't also transparent?

[PTGui Support]

Hi Aaron,

Yes I noticed the black rectangles as well, this is a bug. Will be fixed.

Joost

[aaronpriest]

Hi Joost,

Another question: when saving individual layers as a 16-bit .psb file, can it be done without the masks on each layer? Just the transparency for each layer with no masks? The panorama is too big for individual TIFFs, exceeds the 4GB limit.

Aaron

[aaronpriest]

Oh, another observation, the TIFFs would probably be smaller than 4GB, but they also exhibit the large black areas which fills them with more data. :-)

[aaronpriest]

Scratch this request I guess. The masks exactly equal the image, so it doesn't really matter if it is there or not. Blended great in Photoshop. :-)

[PTGui Support]

Hi Aaron,

I'm sorry, the masks cannot be removed currently. But you might try
packbits compression: although packbits cannot compress 16 bit image
data very well, it can shrink uniform black or white areas to less than
1% of the original size.

And it's not clear if you are talking about PSB or TIFF, but TIFF files
can have LZW compression which is also effective for 16 bit image data.

See the Settings button in the Create Panorama tab.

Joost

[aaronpriest]

I guess what I really need is to be able to save individual HDR layers into a single layered 32-bit .PSB file with transparency like I can 16-bit layers for blending in Photoshop. 32-bit TIFF might work, but then I'm exceeding the 4GB file size boundary even with packbits or LZW compression on most of these large panoramas. Doing any tonemapping of the individual brackets to 16-bit before stitching results in horrible color shifts and banding in water and skies, and having PTGui do the exposure fusion isn't handling blending as well as Photoshop for minor exposure and white balance shifts throughout a large gigapan scene. .HDR has no transparency, and .EXR and .PSB leave really large black areas that have to be removed by hand. You can't do it with a batch script using the alpha channel because that still leaves large chunks of black areas that have to be removed by hand on hundreds to thousands of images. So there is no efficient workflow at this time to export to 32-bit files unless PTGui does the blending.

I'd like to be able to load bracketed 16-bit TIFFs into PTGui and let it do all the alignment and save to 32-bit, but then I can't easily export only 32-bit files and blend in Photoshop. Instead, I have to export each bracketed set as a separate 16-bit .PSB of individual layers, blend each into a large gigapan, and then attempt to tonemap 5 to 7 bracketed gigapans. The memory requirement for that is extreme and most programs choke. Not to mention, most programs require 16-bit TIFFs as input files instead of .PSB and I'm still beyond that 4GB boundary for TIFFs in 16-bit mode for some of these images. So then I'm back to merging my individual bracketed exposures into 32-bit TIFFs before bringing them into PTGui. That seems to be working OK as it still covers the entire dynamic range without any color shifts or white balance changes, I just can't find an efficient way to export them once warped to blend them in Photoshop with proper alpha channels.

Just trying to find an efficient 32-bit workflow for me... :-)