#550|MONOCHROME THREAD|POST YOURS|16Jul2021-23Jul2021

Started 2 months ago | Discussions thread
JimH123 Veteran Member • Posts: 3,131
Re: just tried bypassing the debayering on pp

ivan bayu wrote:

JimH123 wrote:

ivan bayu wrote:

and quite frankly, i haven't see any differences other than capability to pushing more, just like this one

alas, i might do more test...

What do you mean bypassing the debayering?

well, i'm just trying a feature on darktable that called demosaic passthrough...

If the sensor has a color filter array, without debayering, the resulting image will be speckled with 3 shades of pixels all over. Let's suppose you looking at something in the picture that is a solid color - let's pick red for example. And within that space the red covered pixels will record one level, and the blue pixels another level and the green covered pixels yet another level. And when you look at the image real close, you will see this. In fact, RawTherapee will allow you to do this. Sure, the image hasn't been debayered.

is it bypassing a demosaicing process different from bypassing a debayering process? if it was different then i am sorry, i thought it was the same, hehehe

And also the image is not useable.

please explain why the image is not usable.

Is this what you are describing?

Your image was debayered. I looked closely and I don't see what it would be if it was not debayered. Look closely at this crop of your image.

I will show an example of turning off debayering. First, here is an example. I have cropped out a red rose from an image.

Using RawTherapee, I have chosen mono, instead of using a debayering algorithm. Note that in this case, RawTherapee is choosing mono instead of just turning a debayered color image into a B&W image.

Next, I am going to pick the far right petal where there is a constant color and blow it up bigger. Notice the 3 different levels you see. Some are the values seen by red covered pixels, some from blue covered pixels and some from green covered pixels. You image does not show this, so your image is not really debayered. But we do need a definition of what DarkTable means by Bypassing.

OK, I found what you are doing in the dark table manual. See:

Notice that it says that it says that it discards the color information during the Demosaicing Process. This is a fancy way of saying that it is turning the image into a B&W image. But there was indeed debayering that took place. And by the way, debayering and demosaicing both mean the same thing.

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

Now I will take this a step father.  Here is a crop of a red rose taken with a sensor that has been modified to be mono by removal of the color filter array through a red filter which renders the rose as white.

Now a more up close look on the left side.  Notice the detail.  Because there is no demosaicing, detail is much greater.

Finally, to the pixel level.  No pattern of light and dark pixels.

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