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UltravioletPhotography

Passionfruit Flower, Multispectral Triptych


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I found this Passionfruit Flower hanging over my fence today.

So I gave it some treatment with visible & UV light.

 

post-31-0-73408800-1421415851.jpg

post-31-0-25120700-1421415889.jpg

post-31-0-33615900-1421415913.jpg

 

All taken with the Sigma Foveon DP2, APS-C compact, without the internal IRC filter (full spectrum).

First, is in visible light (CFL), camera settings, ISO 100, f8 at 2 seconds, with original IRC.

Second, is in Ultraviolet light (CFL x 2 & 1 x 400 watt, UV party lights), camera settings, ISO 100, f8 at 3.2 seconds, with original IRC + GG420.

Third, is in Ultraviolet light (CFL x 2 & 1 x 400 watt, UV party lights), camera settings, ISO 100, f8 at 13 seconds, with Baader U2. Sorry it is not in proper focus, but the flower was closing up :(

Cheers

Col

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You really caught the gloss on the leaves well in the third shot; it is fascinating how jacking up the air/surface refractive index differential brings out the specular highlights. Is there a reason for the narrowband illumination?

 

The flower seems to have an inverted nectar guide: darker in visible than in UV. Does this say anything about what the pollinators are?

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Thanks Clark

The "narrowband Illumination" is all I have. These lamps are mercury vapor of two different kinds, with Wood's Glass filters. I have a narrower band, MTE U301 365nm LED lamp, which I didn't use here. I am open to suggestions for a better lighting.

I'll keep an eye out to see what bugs visit the Passionfruit Flowers.

Col

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This Passionfruit Flower is interesting for me as it has a 'violet' centre colouring that is very difficult to render in digital images.

The visible light, Passionfruit Flower at the start of the thread I have processed (to the best of my limited ability) to be faithful in colour & white balance.

 

Below is the same visible light, Passionfruit Flower, it is processed to get the closes that I can to the 'violet' as I 'saw' in the flower, but as you can see it has lost the colours in the rest of the flower. I know this is the true 'violet' as I have held the actual flower against the screen & eyed the result, as the same to my eye. Is this just the limit of our colour technology, or can I process this any better, somehow ?

Col

 

post-31-0-64290800-1421485091.jpg

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You could start by using a colour profile for your image. It is untagged. Colour management along all of the work flow is the key to reliable colours.

 

Assigned an sRGB profile it shows a massive cyan dominance. That can easily be taken out by adding red.

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Something similar but not necessarily very close. If you edit in say a wide gamut space such as ProPhoto RGB you'll see colours not present in sRGB. For a web browser to show the image to the closest approximation, the file needs to be assigned a correct colour profile (and the browser supporting colour management).
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Col, tell me what converter/editor you are using so that I can suggest something.

 

It is not unusual for digital cameras to have some difficulties with violet colours.

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Thanks Andrea & Bjorn

The RAW files are opened in the Sigma SPP converter that has plenty of adjustments.

I also have Adobe PhotoShop Elements 11, which I try to learn.

I am aware of the limitations of the colour Violet & the nasty substitute Magenta.

Just for the interested, here is a screen shot of the adjustments in the Sigma SPP RAW converter.

Col

 

post-31-0-70210000-1421539072.jpg

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You can take the foto after its Sigma Pro conversion and change that Magenta colour locally in PSE 11 using the Color Brush.

OR you can use a hue/saturation layer and move the Magenta to Violet.

I think this 2nd method is easiest.

 

*******************

 

On the Layers panel, duplicate the original layer.

On the Layers panel, add a Hue/Saturation layer over the duplicate layer.

On the Hue/Saturation tool:

  • Set Channel=Magenta.
  • Click the Clipping Mask icon on the bottom left.
  • Select the + Dropper and click the various magenta shades in the center of the flower.
    You will see both Red and Magenta intervals appear on the bottom hue bar
    because the center colour of the flower is a mix of both colours.
  • Move the Hue slider to the left until a nice Violet colour begins to appear.
  • Adjust the Saturation slider and Lightness slider to further refine the Violet colour
  • Use a black paint brush to brush away any unwanted colour changes in other areas of the foto.

The Hue/Saturation layer is initially set to a Normal blend. Sometimes a further refinement of the new colour can be made by resetting the layer blend to Hue instead. You have to experiment to see which works best for this foto.

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I forgot to add. Somewhere along the way as Bjørn mentioned you need to embed an sRGB profile if the photo is to be viewed online.
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It is such a stunning flower !!

Years ago when I was living in Arizona I grew one of these on my patio.

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Yes it is a very attractive flower & a nice aroma, I guess that is what it relies on to get the bees to do the pollinating, as it is only open for one day.

Col

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Thanks very much Andrea & Bjorn

I will practice this very day this week & try & get this embedded in my brain.

Yes Bjorn I embedded the sRGB in the image too.

Cheers

Col

 

post-31-0-68553600-1421570868.jpg

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Nice flower shots. I like them both, the uv and the vis shots!

 

You can handle your sigma much better than I was able to do!

 

I always had beautiful colours in my pictures, even if the subject originally was in b&w...

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Thanks very much Stefan, much appreciated.

The Sigma's & I have had a long time to get used to each other, a lot of bad language too ;)

Getting Violet out of an image instead of magenta has been a long quest, & I am very grateful to get Violet now, & with the help here & other friends, over the past year or two.

Cheers

Col

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Col, do let me know how that PSE 11 method works out for you, OK? Thanks.

 

There are other methods across various software. For example, in Photo Ninja you would adjust the magenta & red sliders in the Color Enhancement tool. It is quick and easy, but..... it also is global. So you would have to make two conversions - one with the Violet correction from PN and one without. Then you would need to merge them in PSE layers after selecting the Violet area. So ultimately it makes just as much work as using PSE Hue/Saturation layers as described above.

 

Similarly, you could combine two conversions from Sigma Pro in PSE 11 -- the first one shown with incorrect Magenta and the second one with correct Violet. There are some nuances to combining layers which involve making a good selection of the area to be overlayed. I am not so good at selection in Photoshop myself !!

 

As Bjørn said, profiling the colour in the camera is the way to go. I know that Photo Ninja and Lightroom both have methods for using the Color Checker Passport and variations.

 

These Sigma cameras are tricky beasts. They certainly do provide masses of detail - quite amazing really.

 

******************************

 

Is there a reason for the narrowband illumination?

As Col mentioned, he is using a UV torch. But also, the Sigma Foveon sensor seems to capture most of the UV in the blue layer. That tends to keep things more monochrome looking even in sunlight. Somewhere here Col showed UV fotos made in sunlight with the Sigma cam.

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Col, I forgot to ask this question above - ave you tried an in-camera pre-set white balance with the Sigma DP2 for the Visible shots. That might cure the Violet problem ??
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An interesting experiment. I "applied" an sRGB profile and got this - which looks more violet to me?? Does it to others? Why would "application" of an sRGB profile alter the violet and "embedding" of an sRGB profile would not?

This is the foto from post #17.

 

index.jpg

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Just to clarify the lighting setup used here, for the UVIVF & the UV light photos, all are Woods Glass UV Party lights, left to right....

40w CFL, 26w CFL, 400w HID.

 

post-31-0-29582800-1421631338.jpg

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An interesting experiment. I "applied" an sRGB profile and got this - which looks more violet to me?? Does it to others? Why would "application" of an sRGB profile alter the violet and "embedding" of an sRGB profile would not?

This is the foto from post #17.

 

post-4-0-13352200-1421595201.jpg

 

Yes, I like this Violet much better thanks Andrea.

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Col, I forgot to ask this question above - ave you tried an in-camera pre-set white balance with the Sigma DP2 for the Visible shots. That might cure the Violet problem ??

 

With this UV lighting I can't get a Custom WB.

I started with the cameras pre-set Sunlight WB, but I have moved that with the colour picker.

Col

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