Reducing backscatter using photoshop 7

[SCUBA Chick]

Hi!

We have some good pic's taken with our Sony p12 and sea and sea strobe. However some of the pics are still suffering from a small amount of backscatter...

We were just wondering if anyone out there with access to photoshop knew how to use the program to minimise the backscatter..if indeed it can be done?

Any suggestions would be greatly appreciated

cheers

Scubachick  

[Tim Ingmire]

It can be very difficult, if not impossible, to remove backscatter completely.  Try using the 'clone' tool to just paint over the worst bits.

Really the best way is to prevent backscatter in the first place by changing your strobe position and/or getting closer to the subject.

Can you post a typical picture so that we can see how bad a problem you have?

Tim

[Norseman]

<font color='#0000FF'>Well it all depends on how much back scatter you've got and what kind of background we're talking about.
But here are a few hints:

- Draw around the object you wish to leave clear and reverse image in order to frame all the stuff with backscatter. Copy contents and paste in order to create new layer with only background (in short Control C then Control V)
- Blur background. Sufficient?
- If not sufficient continue by darkening the background either by using contrast/lightness, by using &quot;curves&quot; or by using &quot;levels&quot;. This is where you play around.

Once you've managed to remove the backscatter you can merge the layers again. You might want to work on the edge between the background and the sharp subject of the picture.

If not understood I can try, TRY, to make a tutorial

Kyrre

[beanie]

<font color='#8D38C9'>I do in paintshop
median cut then despeckle and that cuts down on a lot of back scatter

[Tim Ingmire]

Well you do learn something new everyday!

Guys can you post before and after shots using the techniques you've outlined?

[Andy Phillips]

Kyrre's a as good a way as any, I would be more inclined to take the layer, invert it then run a fairly brutal Median filter, re invert and then merge the layers.

This is where Photoshop can trip over and where an image processing package (as opposed to image manipulation)which allows you to threshold out your subject works.

I have included a link for a package called Image J. This is the only true image processing package which is free (as far as I know). This will allow a relatively simple way to cut out your subject.

If I find time in the next week or so I will try to make a makro up.
No promises though. If someone else who has the time to play with it manages it first, Well done.

Personally I use MetaMorph, if you ave a spare £2,500.00 then I will willingly sell you a copy.

Andrew

Image J Image Processing Software

[Norseman]

<font color='#0000FF'>Nowadays I try to avoid too heavy work on the pics, except tweaking of colours as well as exposure.

Nevertheless sometimes you want to &quot;prettify&quot; an bad image.. perhaps that was the only one you got of that oh so rare little thingy?

Here's a very quick one. I didn't use Photoshop, just ARCsoft that came with some camera.

I start off with this image of a collapsed sea-spider.



Then I outline the subject. Roughly, since the edge can be softened afterwards (Not done in this walkthrough)

[Norseman]

<font color='#0000FF'>Further on

Invert the selection (Control I in many cases)



Then Copy selection followed by a direct Paste (Control C then V) which in effect makes a new layer that you can work on. Deselect (Click on the &quot;eye&quot main image (with subject) in order to see what you're doing to the new layer.



Play around a bit with different blurs. I just did a heavy Gaussian blur on this one. Notice that edge gets blurry too.

[Norseman]

<font color='#0000FF'>And finally:

Try darkening the layer by different means. On this I did it the simplest way.



Try seeing both layers together. On this one you can see the difference very clearly. Had the border been closer it would have been less conspicuous.



Finally I darkened the subject in the bottom layer too, in order to get the same shade on both layers.
Finish off by merging the two layers.



As said, this was just a quickie. I think Andy P is onto something when you're talking about actually manipulating the image. Mind you, this is what photographers have been doing since day one.. in the lab one would be exposing the image through a mask in order to make the surrounds less visible.
Actually removing the speckles by &quot;painting&quot; with surrounds could be called manipulation.
But if it makes your picture better, who cares?

[John Gulliver]

I have Photoshop 5 Limited Edition. I don't know if Photoshop 7 is the same but removing backscatter with Photoshop 5 is easy - it has to be, because I often have quite a lot.
I just use the dropper to &quot;suck up&quot; colour from a suitable nearby point then use the paintbrush to paint over the backscatter spots. I can clean up an image with quite a bit of backscatter in a couple of minutes.