9 Replies Latest reply: Apr 23, 2012 6:00 AM by TLL... RSS

    LR import with alpha channel

    TLL... Community Member

      <Lightroom novice> Can I import a tif image with a alpha channel in it? It seems as though LR will accept the image and allow development but when I export it as tif or psd it goes out as RGB only - the alpha channel is gone. I don't really "need" to do anything with this channel in LR but I can't have it disappear either. Maybe a import/export setting issue - I hope so...

        • 1. Re: LR import with alpha channel
          Dorin Nicolaescu-Musteață Community Member

          The alpha channel will be preserved in the original Tiff, but not in the

          exported image. When exporting, Lr bakes a totally new image.

           

          Why do you need the alpha channel in the exported image?

          • 2. Re: LR import with alpha channel
            Brett N Adobe Employee

            A TIFF created by exporting a file from LR will also loose layers. Basically, anything that LR doesn't support (i.e. can be edited in LR) will be left out of any file created by an export.

            • 3. Re: LR import with alpha channel
              TLL... Community Member

              The alpha channel represents additional image data - these are multispectral aerial captures (RGB +IR) that a lot of geospatial data folks are trying to find applications to work with, especially in a pre/post processing workflow. I was really excited to start working with LR as it has sooo many tools for image adjustment. This will be great for RGB imagery, but again we hit a wall with multi-band. Like I said I don't need to do anything with this 4th channel except keep it for downstream work. Now it looks like I need a way to manage two imagery streams, one maintaining the IR channel and one for RGB adjustments in LR. Then creating a hybrid using both in PS?

               

              "The alpha channel will be preserved in the original Tiff, but not in the

              exported image. When exporting, Lr bakes a totally new image."

               

              This first part doesn't make sense - the second part is disappointing...

              • 4. Re: LR import with alpha channel
                Brett N Adobe Employee

                The first part, LR preserves all data, is because LR is a catalog, it merely keeps track of your images, it doesn't edit them (unless you tell it to write metadata changes to the files). Since LR doesn't support alpha channels, this just means that the fact the image has one will be ignored while working with the file in LR. This also means that when LR goes to create a new file, it continues to ignore the alpha channel.

                • 5. Re: LR import with alpha channel
                  TLL... Community Member

                  Hey thanks for the info! I'm OK on the first part (I was being a bit facetious). So, what would it take to include alpha channels in a future version of LR? Even just to maintain image continuity between import/export. For multispectral imagery this could be a godsend...

                  • 6. Re: LR import with alpha channel
                    trshaner MVP

                    LR's non-destructive editing workflow provides a wide-range of tools and output options that work very complimentary with PS, once you understand and accept their differences.

                     

                    Just as you are interested in "preserving" the Alpha channel for later processing, you also want to save the "original" RGB channels. The same issue exists with film scanner IR image information saved to an Alpha channel for later dust spot removal processing.

                     

                    Suggestion: Process the "original" TIFF or PSD file non-destructively in LR in the exact same way as "camera raw" image files. All file "edits" are kept in LR's catalog, which should be backed up along with the unmodified "original" files. You can also choose to write all metadata and Develop changes to the "original" TIFF or PSD file, which is useful if you or someone else want to process the files on another system with LR.

                     

                    At a later date the Alpha Channel information can be applied "non-destructively" in PS using editing layers to "blend" the IR image data. These PS modified files can be re-opened in LR and will now show the applied Alpha channel editing layers. Make any further edits you desire in LR and use the most appropriate LR module to "tailor" the output for your specific usage.

                     

                    I use this editing method with both PS and LR open, which allows real-time preview of the PS edits in LR. Just save the PS (as you make edits) and you will see the file update with the changes in LR almost immediately. I sometimes do destructive editing in PS (i.e. cropping, content aware fill, etc.) when I am sure this is not removing any image information I might need in the future. You can also add a PS backup layer copy when doing any destructive editing, which also lets you do Before and After comparisons. Disk storage is relatively inexpensive compared to the value of your time & patience.

                    • 7. Re: LR import with alpha channel
                      TLL... Community Member

                      Hey thanks a lot for your thoughtful reply. I've read through it a few times now and am trying to get the idea, but still find some issues:

                       

                      "Suggestion: Process the "original" TIFF or PSD file non-destructively in LR in the exact same way as "camera raw" image files."

                      That's what I'm doing and for RGB imagery this is working well. I'm exporting tif images that move on to the next production step (I and Adobe are not involved after this). But as was admitted by Adobe a RGB+IR image will not process without ignoring/deleting the alpha channel on export.

                       

                      "All file "edits" are kept in LR's catalog, which should be backed up along with the unmodified "original" files."

                      OK, got that too. We probably won't save this once the exported images are approved and backed up.

                       

                      "At a later date the Alpha Channel information can be applied "non-destructively" in PS using editing layers to "blend" the IR image data."

                      This is where I'm getting lost. Are you talking about stripping the 'original' alpha channel from the pre-LR image and inserting it into the LR processed RGB image via PS batch/script? That's my thinking as an one approach.

                       

                      "These PS modified files can be re-opened in LR and will now show the applied Alpha channel editing layers. Make any further edits you desire in LR and use the most appropriate LR module to "tailor" the output for your specific usage."

                      No they won't, or do these steps involve only psd files w/alpha channels? The alpha channel (IR data) is still ignored by LR, I have no way to even just keep that information once inside LR nor can I "taylor" a way to save an image with 4 channels of color information inside LR.

                       

                      "I use this editing method with both PS and LR open, which allows real-time preview of the PS edits in LR." Just need to see things once

                      I can see if this is going to work it will be some kind of PS/LR hybrid workflow - but it needs to be simple/sleek/fast as we're talking 1000's of big **s images per project, and many, many projects.

                       

                      Thanks again for your input!

                       


                      • 8. Re: LR import with alpha channel
                        trshaner MVP

                        TLL... wrote:

                         

                         

                        "All file "edits" are kept in LR's catalog, which should be backed up along with the unmodified "original" files."

                        OK, got that too. We probably won't save this once the exported images are approved and backed up.

                         

                        It sounds like you don't need LR's database tools for organizing, adding metadata, or the various Export modules. You could still use LR to expedite Development editing of the RGB image. One possible solution is to Export the LR edited RGB images full size to a separate folder with the same bit depth and colorspace as the original files. Then use a PS Script to Batch Merge the LR export image to a new layer in the original file, something similar to this one:

                         

                        http://forums.adobe.com/thread/546727

                         

                        This way you still have the original RGB image backed up as a layer, which can also be unselected in the merge script.

                         

                         

                        TLL... wrote:

                         

                        "At a later date the Alpha Channel information can be applied "non-destructively" in PS using editing layers to "blend" the IR image data."

                        This is where I'm getting lost. Are you talking about stripping the 'original' alpha channel from the pre-LR image and inserting it into the LR processed RGB image via PS batch/script? That's my thinking as an one approach.

                         

                        "These PS modified files can be re-opened in LR and will now show the applied Alpha channel editing layers. Make any further edits you desire in LR and use the most appropriate LR module to "tailor" the output for your specific usage."

                        No they won't, or do these steps involve only psd files w/alpha channels? The alpha channel (IR data) is still ignored by LR, I have no way to even just keep that information once inside LR nor can I "taylor" a way to save an image with 4 channels of color information inside LR.

                         

                        I have no idea what you will be doing with the Alpha channel IR image data, but I was suggesting to convert the Alpha channel to a layer mask in PS with 'Blending.' This leaves the Alpha channel as a backup of the IR data. Here's a simulated example using a an IR layer mask I created using LR's B&W IR Develop preset:

                         

                        IR Screenshot.jpg

                        IR Screenshot_LR.jpg

                        You can use PS actions with the Batch processor and/or build scripts to do just about anything. In LR you can create Develop presets to apply adjustments across 1,000s of images with a couple of mouse clicks, but no Actions or scripting capability. Like I said, PS & LR are complimentary, but different. I'm not sure which processing methodology is best for your image "end-use" but I hope this gives you some more ideas.

                        • 9. Re: LR import with alpha channel
                          TLL... Community Member

                          Thanks, I'll be looking into all you've shared. I appreciate it!