photo merge in Lightroom

[CatherineA]

Last week I took bracketed photos of a barn at night with its lights on. I took five images from -4 to 4 EV. I thought that I could capture the full range by merging just the +4 EV and the 0 EV images since one had all the shadows and the other had all the highlights. But, the histogram of the merged image indicates that both shadows and highlights were lost. What happened?

[Manfred M]

Catherine - It would be a lot easier to diagnose if you posted the image in question.

I assume that you were trying to photomerge as HDR? If that is the case, the resulting image from this process will end up being very low contrast and combining the two will generally give you a very flat image that requires additional mid-tone contrast to be added.

[DanK]

What do you mean by "lost"? as long as one image didn't clip at one end and the other didn't clip at the other end, you shouldn't loose either end. However, as Manfred said, the composite may not look very good. LR has an "auto" option that does a fair job turning the composite into something close to what one might want.

The best would be to post the images and their histograms.

[CatherineA]

Catherine - It would be a lot easier to diagnose if you posted the image in question.

I assume that you were trying to photomerge as HDR? If that is the case, the resulting image from this process will end up being very low contrast and combining the two will generally give you a very flat image that requires additional mid-tone contrast to be added.

Manfred, I think I have just across my answer. It seems that when there is an HRD merge in LR the exposure slider has a much larger range. It goes from -10 to 10 stops instead of from -4 to 4.

[Manfred M]

I rarely use HDR, but when I do I tend to stick with a maximum of a 2-stop bracket as this provides the software with enough data to do smooth transitions. Four stops is pushing it a bit. More data tends to be better than too little and I have always used at least 3 different exposures as input.

[CatherineA]

Thank you Manfred. I did try to post the images and histograms as you and Dan suggested however I struggled with TinyPics on this occasion. I got the images up but not the histograms.

The five photos I ended up merging were taken at 2-stop increments: -4, -2, 0, 2 and 4 EV.

[Polar01]

I think I know what is happening, I do not use LR, however I do use PS. In PS if I do a HDR type of shot, I save it as a Tiff file, then reopen it in ACR, it now opens with instead of 10 stops 5 up & 5 down it opens with 20 stops 10 up and 10 down. I believe that when LR creates the image, that image is automatically save as a Tiff. This then allows LR to have 20 stops instead of the usual 10 stops.


Cheers: Allan

[DanK]

I think I know what is happening, I do not use LR, however I do use PS. In PS if I do a HDR type of shot, I save it as a Tiff file, then reopen it in ACR, it now opens with instead of 10 stops 5 up & 5 down it opens with 20 stops 10 up and 10 down. I believe that when LR creates the image, that image is automatically save as a Tiff. This then allows LR to have 20 stops instead of the usual 10 stops.


Cheers: Allan

The file is stored as a DNG. I think it's a different process entirely than the one used in PS. I see no color distortions in the LR merge, but I did see clear distortions when I did HDR in PS several years ago. In fact, the "HDR" in LR gives results that often look like exposure fusion rather than HDR. I sometimes do both to compare them.

[Polar01]

Dan when you create a DHR image in LR, I believe it can not be stored in the original format that LR uses to store data. This is because LR had created a whole new image using the data of 3 or more files. It has to stored it as some kind of format so that it can used Opening a DNG file in the LR converter will not give you 20 steps of exposure only 10 steps. Open a file in a tiff format and you get 20 stops of exposure. I could be wrong but I can not think of reason to store the newly created file as a DNG instead of a Tiff.


Cheers: Allan

[DanK]

Dan when you create a DHR image in LR, I believe it can not be stored in the original format that LR uses to store data. This is because LR had created a whole new image using the data of 3 or more files. It has to stored it as some kind of format so that it can used Opening a DNG file in the LR converter will not give you 20 steps of exposure only 10 steps. Open a file in a tiff format and you get 20 stops of exposure. I could be wrong but I can not think of reason to store the newly created file as a DNG instead of a Tiff.


Cheers: Allan

Allan,

Lightroom has no "file save as" or "file save" function. In normal editing, it leaves your raw file alone and simply stores your edits, either in the catalog or in XML "sidecar" files (user's choice). The only way to create another file is to export.

When you use the Photo_Merge_in_HDR function, LR does create another file, but it is not under the user's control. This new file, which is a DNG file, is created automatically by the merge routine.

As someone pointed out, the editing controls are different. For example, in editing a original raw file, the exposure slider has values from -5 to +5. In editing the DNG that has been created automatically, the values range from -10 to +10.

AFAIK, the only opportunity to create a TIFF file in Lightroom is via the Export command, which is not used in the HDR merge process.

Dan

[Antonio Correia]

I made a new thread after reading this one. If you care to read... thank you