Monochrome issue on converting NEF to JPEG in PS CS6 64bit on Win8 64bit

[shariff tebio]

Good day everyone,

i know this would be the right place to ask on my issue on converting NEF to JPEG, i took some monochrome shots and tried to convert it to JPEG on CS6 64bit, but the final output is that CS6 converted it to colored and also during preview, do i have compatibility issue on my OS or 64bit? or do i have to change some setting on CS6 during batch processing?

thanks in advance

[revi]

A raw file (and NEF is a raw format) is always in colour, even if you set the camera to B/W. So it's normal you have to convert to
B/W in CS6. (note that the JPEG embedded in the NEF should be in B/W, but that will not be shown as the preview while converting
the raw file)

Some RAW formats/cameras might indicate in the metadata if an image was shot as B/W, and then the raw converter could do the
conversion to B/W automatically. I'm not sure that would be desirable behaviour though.

First, there are several ways to convert to B/W. The easiest is desaturation, but that often gives the least interesting result. Using
the channel mixer is a bit more complicated, but gives more possibilities (you can decide which colour channel will contribute most to
the B/W results, and you can play with the tone of the image). Then there are possibilities to imitate several B/W films, etc.

Also, you might want to do some editing on the colour image first (WB setting, and such) to get the best basis for the B/W conversion.

So, no, it's not a 64-bit problem, nor does it indicate a compatibility issue.

[shariff tebio]

i was not really wrong in asking it here, thank you so much revi for the explanation, i hope those inquiries are not so dumb, i have just started photography and CS6, i still got ton's on learning to be done in CS6.

again your explanation is highly appreciated, others are welcome to add information or explanation.

[Mike Buckley]

i hope those inquiries are not so dumb

Welcome to CiC, Shariff. One of the mantras here is that there are no dumb questions. I've never seen a response here that didn't try to helpfully respond to a question, no matter how simple or complex the question seems to be. Revi's great advice, of course, is no exception.

[shariff tebio]

thanks mike

[mrrod]

I remember coming across this issue myself, taking a b/w in camera and the raw being colour; Can anyone enlighten me as to why a camera would have the ability to take a b/w photo and yet having to convert the picture from colour to b/w in process.

[davidedric]

My simple answer is that a digital camera can't take a black and white image. A physical grid in front of the sensor allows only light of one of three colours to stimulate the receptor underneath. Hence you have to reverse that process to get the b&w image.

[Mike Buckley]

I wonder if perhaps it helps to realize that most digital cameras are built with a sensor as described by David to record colors. Some digital cameras (or at least one I read about) are built with a sensor that records only luminosity (not color), the result being that the image is in black-and-white and cannot be converted to color.

[revi]

Both of the last two answers boil down to the same thing:
the camera sensor only sees and records luminosity, and cannot distinguish colours/wavelengths (leaving aside the foveon sensor).

But most cameras use a grid of coloured filters (bayer matrix) to get the colour information. The presence of the filter grid means that you cannot just grab the raw camera data and treat them as a B/W image. So you have to start treating the image as a colour image, then convert to B/W...

To show the differences, here's a composite with a colour image, the same converted to B/W and the corresponding RAW data, extracted with 'dcraw -D':


There's a clear grid apparent in the RAW data, especially in the red areas, that is due to the bayer filter: the red parts have very little blue in them, so those pixels will be very dark in the RAW data. Red and green are present, leading to a visible grid. In areas of low saturation there is less of this grid appearance.

Edit: These are 100% crops, The grid is exaggerated on the down-sized in-line version, to see the actual appearance, use the light box, please.

[shariff tebio]

Thank you so much david, mike and revi for additional information and explanation.

The presence of the filter grid means that you cannot just grab the raw camera data and treat them as a B/W image. So you have to start treating the image as a colour image, then convert to B/W...

i hope you dont mind guy's i have a follow up inquiry which i will focus on the "FILE" which is NEF and to "APPLICATION" Photoshop relationship, the qoute above Revi, is the application doing this to a file also? what i mean is that Photoshop only sees the NEF as Colour not B/W, so does this explain why during conversion(NEF to JPEG) the output is colored? because i did also try to directly preview the B/W NEF using PS and other application and they showed the same output B/w to Colour, instead of the B/W output.

i hope i made my inquiry clear to you guy's

thanks again

[revi]

NEF files are raw files. Raw files have three kinds of information inside:
- the raw sensor data (i.e. intensities measured at each photosite)
- metadata containing camera information and settings (camera make and type, WB, Fstop, exposition time, ....)
- and a jpeg preview image developed in-camera according to the settings in effect when taking the shot.

In your case, you set the camera to take B/W pictures, so the jpeg preview will be B/W, and the metadata will
contain that information as well (for my Sony, that's under 'color mode' and 'color reproduction' in the 'maker notes').
But, this setting has no effect whatsoever on the raw sensor data. So a program that works with the raw
data has a choice:
- it can ignore the metadata and do its thing with just the raw data,
- or it can use some of the metadata to have an initial guess for things like white balance,
- or it can use a maximum of metadata to reproduce the in-camera jpeg.

Problem with the last option is that the meanings of things like scene modes and B/W conversion aren't public, the
camera manufacturers tend to consider those things trade secrets (or at least give that impression*), so a 3-rd party
program (like photoshop) would have to guess as to what methods are used for scene modes. The raw converters
provided by the camera manufacturers can and often do take into account the scene modes.

Afaik, most 3rd-party programs just ignore those scene settings and present a 'default' colour image, for you to
adapt according to taste (which is one of the reasons to use RAW in the first place ).

*) There's a section in the EXIF data that's labeled 'Maker notes'. And it's rather hard to figure out what's in there:
there's no specification available, and some even encrypt the data; it took a few years for the Sony Makernote data
to be reverse engineered, and the flags indicating a B/W setting are in there...