Creating Layers for A Trous Wavelets

[Radar]

Hi Pteam, I am trying to use the Wavelet function.

I have been reading the tutorials and find them very helpful.

So far, this is how I am approaching Wavelets. When I try to create a preview so that I can create layers at different levels, I use the "New Preview Mode" button, then drag a green colored preview square over my entire image.

This creates a preview image.

Then I click the preview tab on the left hand side to select the preview image.

Then I adjust the settings in the "A Trous Wavelets" settings box, and apply them to my preview. But the settings don't split my image up into different layers (wavelet planes) at different levels, like in the tutorial.

It just changes the overall image. I have the count set at four, so I am confused as to why I am not getting four wavelet planes?

What am I doing wrong?

I know its probably something really simple, lol.

So far, its brilliant software. Extremely powerful. I can't wait to get good with it.

Thanks in advance for any help.

Ray

[Juan Conejero]

Hello Ray,

Thank you for your nice comments.

To view individual wavelet layers, activate the layer preview mode on the À Trous Wavelets window: just click the Preview check box that you'll find at the upper right corner.

In this special mode, the currently selected layer is isolated to allow evaluating its contents. Note that an inverted image is always generated in this mode. This has been done this way intentionally, to keep you informed that what you're obtaining is not an actual processing result.

This layer preview mode was used to produce the figures in the documentation. We created a preview as you have described (New Preview mode), and then we used the layer preview mode to isolate a set of wavelet layers. The Preview > Make Image main menu option helped extracting the layers into individual images.

Note that if you modify some parameters for a given wavelet layer (bias, noise reduction, etc.), these parameters are also applied in layer preview mode. This can be useful to evaluate how noise reduction and bias are performing in difficult cases.

Finally, don't confuse the layer preview mode of wavelets with preview objects; both things have nothing to do (e.g., you can apply wavelets in layer preview mode to an entire image, though doing so is very infrequent).

Hope this helps.

Best,

[Radar]

Hi Juan, thanks for your reply.

To view individual wavelet layers, activate the layer preview mode on the À Trous Wavelets window: just click the Preview check box that you'll find at the upper right corner.

I have the preview box checked, and then when I goto apply the image to a preview, it just seems to change into a negative image. But I'm still not getting numerous images like in the tutorial.

Also, what is the slider bar for that is under the "Preview" check box?

In this special mode, the currently selected layer is isolated to allow evaluating its contents.

Does the 'currently selected layer' mean the preview i've created and have currently selected? Or does it mean a 'wavelet plane'?

This layer preview mode was used to produce the figures in the documentation. We created a preview as you have described (New Preview mode), and then we used the layer preview mode to isolate a set of wavelet layers. The Preview > Make Image main menu option helped extracting the layers into individual images.

When I goto "make image" I just get an exact copy of the negative preview image. Should I be doing something else here?

Finally, don't confuse the layer preview mode of wavelets with preview objects; both things have nothing to do (e.g., you can apply wavelets in layer preview mode to an entire image, though doing so is very infrequent).

When you say "preview objects" I take that to mean the previews I've created and not wavelet planes. Is this right?

Thanks again for your help. I'm very new to digital processing, but I am enjoying the learning curve associated with it.

Ray

[Juan Conejero]

Hi Ray,

I have the preview box checked, and then when I goto apply the image to a preview, it just seems to change into a negative image. But I'm still not getting numerous images like in the tutorial.

That inverted (negative) image is precisely a wavelet layer. Well, speaking more accurately, it is a visible representation  of a wavelet layer, that you can use to inspect the image structures it contains.

There is no way to automatically split an image or preview into a series of wavelet layers in a single operation. You have to obtain one at a time and then use the Preview > Make Image menu option to extract it into a new window.

The next versions of PixInsight will include this automatic extraction feature and much more extended capabilities for wavelets processing. Basically, you'll be able to work with wavelet layers as independent images.

Also, what is the slider bar for that is under the "Preview" check box?

It is a simple gamma adjustment. Sometimes a wavelet layer is hard to inspect because its contrast is very poor. By increasing the gamma slider control you can make it more easily visible.

Does the 'currently selected layer' mean the preview i've created and have currently selected? Or does it mean a 'wavelet plane'?

I meant the wavelet plane (you can call them planes or layers, both words are valid) that is currently selected on the À Trous Wavelets window.

When I goto "make image" I just get an exact copy of the negative preview image. Should I be doing something else here?

No, that exact copy is just the wavelet plane you are looking for. The only thing you might want to do is inverting it to get a positive image (press Ctrl-I, or use Image > Invert). This is what we usually do when we put examples on tutorials and processing examples.

When you say "preview objects" I take that to mean the previews I've created and not wavelet planes. Is this right?

Correct. Preview objects are the volatile subimages that you create within a window by using the New Preview mode.

Thanks again for your help. I'm very new to digital processing, but I am enjoying the learning curve associated with it.

Thank you for your interest. You'll enjoy it much more as you gain experience and knowledge.

Regards,

Juan

[Radar]

Great Juan, I've finally got it.

Phew! Can't wait to start processing my images with it.

 :lol:  :lol:  :lol:  :lol:  :lol:  :lol:  :lol:  :lol:  :lol:  :lol:  :lol:  :lol:  :lol:  :lol:  :lol:  :lol:  :lol:  :lol:  :lol:  :lol:  :lol:  :lol:  :lol:  :lol:  :lol:  :lol:  :lol:

Thanks again.