How to add color?

[Nova2000]

Hi. 

I don't use a ccd and don't intend to use one until I learn the basics. 

My questions are regarding a mono ccd

A mono gives black and white images of the object I want to shoot. 

Astrophotographers add filters such as Rgb and they get a black and white image of the dso in the respected spectrum. 

How do you'll colorize a black and white image? 

[johnrt]

You use a software program such as photoshop and place the aligned mono channel from each filter to the corresponding channel, and you have a colour image. 

[carastro]

I use this excellent tutorial by Anna Morris.  I think there are other softwares that will do it too, but this will give you the principal of how it works.  YOu can do the same with narrowband, substituting Ha, Oiii and Sii for RGB, or Sii, Ha, Oiii if you want to do Hubble palette. 

http://www.eprisephoto.com/create-lrgb

[Nova2000]

So basically we add color to the images.?  Does software like pixinsight do this? 

[cjdawson]

Bascially, yes you add the colour.

Think of it like this.  Get three torches.  In front of one, stick a red filter.   In front of the next, sick a Green filter.  And in front of the last stick a Blue filter.

If you turn all three torches on and focus them on the same spot, it will show white light.

you can change the colour, but turning off different lights.  To increase the number of colours you can make, play with the brightness of each torch.

 

When you take photos using a mono camera, by placing filters in front, you are doing exactly the same thing.   So when you combine the images together in photoshop or other programs (I'd be surprised if PixInsight can't do it but would need someone with the software to know for sure)   you are adding the false colour to recreate what was captured.

[johnrt]

28 minutes ago, Nova2000 said:

So basically we add color to the images.?  Does software like pixinsight do this? 

Erm no, I don't agree. If you are making a purely RGB image then you are creating the colour, not adding it. Every colour image in photoshop is made from 3 channels applied to the red / green and blue. You are creating these channels yourself with the use of filters & simply applying them to where they belong in the software to create your colour image.

You are only adding colour to an image of you start to use Luminance.

Yes Pixinsight can also do this, use the channel combine tool.

[Cornelius Varley]

37 minutes ago, Nova2000 said:

So basically we add color to the images.?  Does software like pixinsight do this? 

Are you trying to create a colour image from a single monochrome image or combining separate mono images taken through RGBL filters to produce a colour image ?

[Nova2000]

23 minutes ago, Cornelius Varley said:

Are you trying to create a colour image from a single monochrome image or combining separate mono images taken through RGBL filters to produce a colour image ?

Hi. I don't do ccd imaging I'm just curious to know how it works. And yes images taken from rgbl images off course. 

Rajesh 

[Cornelius Varley]

OK. The RGB mono images represent the values of red, green and blue in a colour image as gray scale mono images. In the image processing software these gray images are combined into a single image in the red, green and blue channels. Once the separate channels are aligned the colour image is created.

[Nova2000]

What color will be the HA and O3 images in? By Color i  mean should they be blended with. the red channel and green channel respectively

[ollypenrice]

It's important to be clear that ALL electronic cameras are monochrome, including DSLRs and 'one shot colour' CCDs. We don't 'colourize' * and we don't invent colour. We measure it.

In terms of colour there is no significant difference between a mono and a 'one shot colour' camera in terms of how the colour is obtained. Both use a red filter to block green and blue, a green filter to block red and blue...etc.

In a 'one shot colour' these filters are placed over each pixel in a 'Bayer Matrix.' Red, green, green, blue - repeated across the chip. (Why two greens? Because it works in the daytime but is a very bad idea at night!) In a mono the imager shoots through an R then a G then a B in turn and combines them later - but the idea is the same. The same kind of software calculates how to weight the three colours of light.

My main point here is to stress that there is no such thing as an electronic colour detector, as yet. They are all mono and they all use filters to work out the real colour.

Olly

* That is, in natural colour imaging, which is what I do in deep sky photography. I have invented colour from purely mono images in solar imaging. This is always declared. The colour in this image is pure invention:

 

[ollypenrice]

2 hours ago, Nova2000 said:

What color will be the HA and O3 images in? By Color i  mean should they be blended with. the red channel and green channel respectively

Ha is very deep red and I will always add it to the red channel. I don't like to add it to luminance, which is the lighting across the full range of colours. OK, I may use a whiff as luminance on some targets but it ain't right!

OIII lies on the blue-green border (sometimes called teal blue) so I add it to both green and blue but in separate images which I then blend to taste.

Others will use different methods.  When I add narrowband I have the natural colour image on another screen and try to respect it when adding NB.