Confused about export to Photoshop??

[ftherrmann]

After doing a DBE, screentransform and histogram stretch I save the file as a 16bit tif for use in Photoshop CS5.  Sometimes this will lead to a file that may or man not display correctly in both Win8 explorer and CS5.  By incorrectly I'm refering to an image with little or no luma data.

When the above doesn't work doing a HDRTransform before the image is saved to tif often fixes the problem.  Sometimes this also doesn't work and I export the fits file to CCDStack and then export to tif.

My understanding was that once an image goes non-linear (ie. screentransform or HistoStretch) you should be able to save to tif and basically see the same image that was displayed in PI as a fits file.  Apparently this isn't always the case.

Could someone please tell me the correct procedure for getting a "What you see is what you get" when saving from fits to tif in PI?

[Philip de Louraille]

I think it may be possible that you have a "double" stretch going on because that has happened to me before.
For example, I have used STF to stretch an image (which happens only in memory...) and then I used histogram stretch - FORGETTING that I then had to reset the STF so that the image is not visually showing both processes. If this is so and you save the image, when you reopen it, the STF effect won't be present and your image will not be "stretched" as you thought.
Just an hypothesis.

[Josh Lake]

Could someone please tell me the correct procedure for getting a "What you see is what you get" when saving from fits to tif in PI?

I believe you must save as a 16 bit TIFF, no higher, for it to work in PS.

[ftherrmann]

I'm aware of the 16 bit limitation to the tif format as I stated in my initial question.

When I bring a fits into PI and do a histogram stretch and save as a tif it opens correctly in CS5. 

If I do a screentransform with the same fits file and save as a tif it does not save the screentransform "stretch".

If I drag the screentransfer function instance to the histogramstretch and execute and then save as tiff the stretch is also not saved correctly.

I've watched several tutorials and do not understand the purpose of the screentransfer function since it apparently is similiar to the histogram stretch with the exception that you can't save it as a 16 bit tiff.

What am I missing?  Could someone please explain this to me or direct me to a faq or url which does?

TIA

Fred

[ftherrmann]

PS:  Every image processing program with the exception of PI has an AutoStretch histogram feature.  Is an autostretch available in PI? 

I thought that dragging the screentransfer instance to the histostretch was a substitute for an auto histostretch, but as I mentioned above the stretch does not get saved when writing out as a tif file.

[Yuriy Toropin]

...Philip described solution above, Ok, let me repeat it...

I thought that dragging the screentransfer instance to the histostretch was a substitute for an auto histostretch, but as I mentioned above the stretch does not get saved when writing out as a tif file.

After drag-N-drop of the STF instance to the HistogramTransform process window you have to apply the histogram transform process (with settings from STF) to the image. Drag-N-Drop the HistogramTransfer instance to the image or press Apply (F5).
After desired HistogramTransform (with parameters from STF) will be applied to the image you will see the "burned" image until you will reset STF to initial linear state. If you will save the image as TIFF after histogramtransfer was applied to it you will have properly stretched image that you  can successfully open in any software.

STF doesn't affect image, it defines only representation on the screen.
Any process should be applied to the image to have some effect on it.

[Philip de Louraille]

Fred,  an STF is a histogram stretch that exists only in memory and is displayed on the screen. It does not affect the file, just its screen image (hence the name Screen Transfer Function)
Why? Because it lets you see the details of an image while it remains linear (dark!) . You can then apply background correction, subtraction, color correction, noise removal and see the effects of those *while the image remains linear. You can save it, all the processes you'll have done will be saved *but* for the stretch.
Then if you like what the STF has done, you can transfer the STF parameters to HistogramTransformation (or whatever name it has today.) but doing this stretches the image twice: one on the screen and now one for the file. So you then need to reset the STF to zero (no effect).
Or you can reset the STF and then do an AutoHistogram to start with and then finish with HistogramTransformation, ... etc.

STF is very powerful for letting you see what is happening to an image while it remains in its linear condition.
Before PI came out, I was using other programs but all my corrections were done *after* I had stretched it (and so were the noise and artifacts.)
PI lets you do those while the image remains linear.
Cheers,

[ftherrmann]

Thanks for the help eveyone.  I think everything finally sunk in.    The double screen stretch shown in PI when dragging the STF instance over to the HTF and executing was throwing me a bit.  Even though it displays with a double stretch it does save as a single stretch tiff.  Doing a reset of the STF brings everything back together again. 

I remembered the "reset the STF" from the tutorials but didn't really grasp what the tutorial was trying to emphasize.  The key is to keep in mind that STF is, as was mentioned, a "non-linear" preview of a still "linear" image.  You basically don't set the image in concrete until you do that last HTF and save to tiff.

PI is a great program, just a little bit of a learning curve.  I'm ready to press the buy button now!

Thanks again,

Fred

[Josh Lake]

Glad you worked it out!  Now it's time to do your post-processing in PI!