M51 (LHaRGB) 26 April 2020

[Laurin Dave]

1 minute ago, geoflewis said:

Thanks Dave,

I think I follow this, at least the bit about which is channel set to lighten and where it is placed in the HaR stack, however, I'm a bit confused by the part that I've highlighted in bold italics above. Are you building an RGB image from mono data first, then stretching that before splitting out the red to combine with the Ha, or is your data from a DSLR or OSC camera?

Hi Geof

Yes I build my RGB image from mono data in Pixinsight, I then lightly stretch it and move to Photoshop ..  In Photoshop I then enhance the colour by making two copy layers..  making the top one Soft Light..  then merge the top and middle layer... then turn the newly created layer to blend mode Colour and flatten the image  ..  Another great technique learned from Olly..  I then duplicate this image .. split the channels and discard Green and Blue

Dave

 

[geoflewis]

13 minutes ago, Laurin Dave said:

Hi Geof

Yes I build my RGB image from mono data in Pixinsight, I then lightly stretch it and move to Photoshop ..  In Photoshop I then enhance the colour by making two copy layers..  making the top one Soft Light..  then merge the top and middle layer... then turn the newly created layer to blend mode Colour and flatten the image  ..  Another great technique learned from Olly..  I then duplicate this image .. split the channels and discard Green and Blue

Dave

 

Ok, now I'm even more confused, sorry Dave. How do you build the final colour HaRGB image if you've discarded the Green and Blue? You've ended up with a colour processed  'stretched' Red, which you blend with the lighten mode Ha, which from your earlier note has also been stretched to taste. How is the HaR combined with / added to the colour image? I'm missing something here I think.... 🥴

[ollypenrice]

Once the LRGB is fully processed I split the channels, activate red, paste the Ha on top of it and set the blend mode to Lighten.

I can click it on-off to see what it's doing. I don't want it to lighten the sky so, if it is, I can black clip it a tad or use curves and lower the bottom. Maybe it's not doing much? In that case I'll pin the background where it is in curves and stretch it above that till it's making a difference. You can stretch it above the noise floor so long as the noise is only affecting the darker parts of the Ha. These won't be applied to the red channel where the red is lighter than the Ha.  With galaxies, where the Ha tends only to be bright blobs, you can stretch the hell out of it! Flatten Ha onto red and merge channels in RGB. If the Ha has come out with too much force it doesn't matter in the slightest. Just paste the new HaLRGB onto the original LRGB and reduce its opacity to taste.

Olly

[Laurin Dave]

Oh dear sorry Geof..    You make your RGB image …  then make a duplicate of it as a separate image and split the duplicate into R,G and B channels - its the G and B from the duplicate that aren't needed..  just the Red.. which after having the Ha added is pasted back into the Red channel of the original RGB image..

[geoflewis]

9 minutes ago, ollypenrice said:

Once the LRGB is fully processed I split the channels, activate red, paste the Ha on top of it and set the blend mode to Lighten.

I can click it on-off to see what it's doing. I don't want it to lighten the sky so, if it is, I can black clip it a tad or use curves and lower the bottom. Maybe it's not doing much? In that case I'll pin the background where it is in curves and stretch it above that till it's making a difference. You can stretch it above the noise floor so long as the noise is only affecting the darker parts of the Ha. These won't be applied to the red channel where the red is lighter than the Ha.  With galaxies, where the Ha tends only to be bright blobs, you can stretch the hell out of it! Flatten Ha onto red and merge channels in RGB. If the Ha has come out with too much force it doesn't matter in the slightest. Just paste the new HaLRGB onto the original LRGB and reduce its opacity to taste.

Olly

Thanks Olly, so this is a completely different method to what I'd envisaged. When you and Dave said combine Ha with R using lighten mode, I thought that you both meant build an HaR stack BEFORE creating the colour image, i.e. make the HaR stack and use that as surrogate R to be combined with G and B. Process that HaRGB image, then layer the separately processed L. I need to start over and I don't think that I can do what you've suggested using ImagesPlus, it sounds like a PS only process.

Many thanks, I need to get my thinking cap on again.......

[geoflewis]

7 minutes ago, Laurin Dave said:

Oh dear sorry Geof..    You make your RGB image …  then make a duplicate of it as a separate image and split the duplicate into R,G and B channels - its the G and B from the duplicate that aren't needed..  just the Red.. which after having the Ha added is pasted back into the Red channel of the original RGB image..

Thanks again Dave, I think that I now follow what you and Olly have both described. It was a case of me not only not playing the same game, but also not being on the same pitch, nor in the same country, nor possibly on the same planet. I'm glad I asked as I'd never have got there with all the flailing around that I was doing trying to get a usable HaR to combine with the GB....

[Stub Mandrel]

Well done Geof, that goes very deep. Wish I had the patience to collect that much data!

[geoflewis]

20 minutes ago, Stub Mandrel said:

Well done Geof, that goes very deep. Wish I had the patience to collect that much data!

Thanks Neil, I'm glad you like it. Where I've just been ticking off Messier targets for my collection, then 3 to 5 hours (sometimes much less) is sufficient, but for some of these spectacular targets I've started to go deeper over the last year or so.

[SyedT]

Incredible image as usual, Geof! I just had a play with Topaz Denoise, seems to do a very good job but creates a very smooth background, almost artificial-looking. What are your thoughts?

[geoflewis]

54 minutes ago, SyedT said:

Incredible image as usual, Geof! I just had a play with Topaz Denoise, seems to do a very good job but creates a very smooth background, almost artificial-looking. What are your thoughts?

Thanks. I've had a similar experience with Topaz Denoise (TD). At first look it seems very good, but less so under zoom. I like to use the side by side to monitor the effects then swap to single view and use the 'Original' button to toggle between original and adjusted views. Like most astro tools each image requires it's own careful application of TD. My recent experiments have been to drop the noise and sharpening sliders right down to below 5 (even 0 and 1), then push the preserve original up above 50, 60 or even more. That seems to give a better blend, but it's early days for me and my trial is about to expire, so I'm going to have to decide whether I want it. Some of the better planetary imagers seem to swear by it, but there is usually no background in those or its taken down to black, so I'll likely purchase it mainly for that, but I think it also improved a couple of my DSO images, so for 80 bucks maybe it's not too pricey.

 

[SyedT]

8 minutes ago, geoflewis said:

Thanks. I've had a similar experience with Topaz Denoise (TD). At first look it seems very good, but less so under zoom. I like to use the side by side to monitor the effects then swap to single view and use the 'Original' button to toggle between original and adjusted views. Like most astro tools each image requires it's own careful application of TD. My recent experiments have been to drop the noise and sharpening sliders right down to below 5 (even 0 and 1), then push the preserve original up above 50, 60 or even more. That seems to give a better blend, but it's early days for me and my trial is about to expire, so I'm going to have to decide whether I want it. Some of the better planetary imagers seem to swear by it, but there is usually no background in those or its taken down to black, so I'll likely purchase it mainly for that, but I think it also improved a couple of my DSO images, so for 80 bucks maybe it's not too pricey.

 

"Like most astro tools each image requires it's own careful application of TD". Completely agree with this statement. I just trialled it out on multiple images. On Milky Way images the auto settings do a remarkable job. Less so for DSOs with variable dynamic range. I'll have a play with it, but I reckon this one's a keeper!

[SyedT]

27 minutes ago, geoflewis said:

Thanks. I've had a similar experience with Topaz Denoise (TD). At first look it seems very good, but less so under zoom. I like to use the side by side to monitor the effects then swap to single view and use the 'Original' button to toggle between original and adjusted views. Like most astro tools each image requires it's own careful application of TD. My recent experiments have been to drop the noise and sharpening sliders right down to below 5 (even 0 and 1), then push the preserve original up above 50, 60 or even more. That seems to give a better blend, but it's early days for me and my trial is about to expire, so I'm going to have to decide whether I want it. Some of the better planetary imagers seem to swear by it, but there is usually no background in those or its taken down to black, so I'll likely purchase it mainly for that, but I think it also improved a couple of my DSO images, so for 80 bucks maybe it's not too pricey.

 

Found a discount code for it, gives 15% off all items! Code is rad15

[silentrunning]

That looks great Geof, really nice deep image with great colors.