changes during converting RAW files

[Ray Rozema]

:):)Hello

I have seen others talk about making changes when they convert the RAW file, such as changing the exposure level. I have two questions about this;
What is the advantage of doing this during the conversion process versus doing it in the editing program?
I use NX2 and I don't see any point in the process where I can make changes during the conversion process. Is there a way to do it in NX2 and waht are the advantages?

I look forward to your answers, and advice.

Thank you very much
Ray Rozema :)

[Roger Clark]

Ray,
Here is my take on it.

If your output from the raw converter is an 8-bit file, it is best to do as much as you can in the raw converter because you will lose data on the 8-bit conversion.

If you are going to output a 16-bit file, you should not lose any data (from 12-bit or 14-bit cameras) so it is less important to do everything in the raw converter, WITH the following exceptions. My experience is with photoshop and I'm talking about CS4 specifically and the Adobe Camera Raw (ACR) that comes with it.

The exposure slider. Digital camera sensors respond linearly, so changing exposure should be changing things on the linear data, not the gamma corrected data that is the result of the output. Thus, changing the exposure slider should result in the same thing as if you changed the exposure time of changed the light levels with f/stops. (Note: I have not verified that ACR actually does this.)

Chromatic aberration correction: do this in the raw converter because you are working on the original data array with the positions of the red green and blue sensors. Chromatic aberration makes the images at different colors different in size in the focal plane. Correcting the raw data in the raw converter corrects those image sizes so they register. That should make the interpolation of the red, green, and blue pixels into the RGB image more accurate.

Beyond that, make sure no data are clipped, and converting to 16-bit data space gives you the precision to do other corrections in your favorite photo editor.

[Ed Cordes]

I could be wrong, but I don't think people are referring to changing things during "conversion" but rather changing settings while using the RAW converter. In Light Room and ACR once the image opens there are sliders available for various adjustments to make to the RAW image before sending it to an external editor like PhotoShop. The advantage is finer control over the details by adjusting things using the original data rather than data that is further interpolated by the editing program.

[Dave Phillips]

all digital images start as RAW data.....either the camera converts/compresses it
to a jpeg or you do. By you converting it, you can make all major adjustments
to never compressed data with full control

[Robert Amoruso]

I find that I generally have better control and results doing most of my processing in PS. In ACR I will use the recovery slider to correct for any clipped channels and the exposure and black sliders for the reasons Roger mentioned. Other then that it goes to PS. The chromatic abbreviation issues Roger mentioned is a new one on me and I will be investigating that.

The above assumes a RAW file into a 16-bit PS workflow.

[Nancy A Elwood]

Ray there is an exposure slider in nx2 that is only there with a NEF, not a Tiff or jpeg.

[Ray Rozema]

Thanks to everyone for the information and advice

Ray Rozema

[Roger Clark]

The chromatic aberration tool is pretty neat. It can transform an image into a much sharper one. For example, I use a 28-135 IS lens which is pretty good for the price. It suffers from a little chromatic aberration. But fixing it in ACR is quick and makes the resulting image much sharper, equivalent to a much more expensive lens. I find that the settings for correction are the same for many images I shoot, so I wrote them down and dial that in for any new image. I rarely have to change those settings. I bet it would make the 28-135 stack up against a 24-105 L IS with this correction, but you have a lighter, smaller lens if that is important.

One might also use it on TC images, especially 2x TCs to improve image quality.

Roger

[Sabyasachi Patra]

I agree with Roger. I was recently clicking with my 28-135 and found that around the high contrast borders there is purple fringing. I used Lightroom for that. This was new to me as I don't often use the 28-135.

Cheers,
Sabyasachi