Wednesday, September 27, 2017



WHY I SHOOT RAW
By john gilbert

I have said it before and I will repeat it now, shooting in jpeg throws away valuable recoverable data.  Furthermore, when you shoot jpeg you are letting the camera “post process the image for you”.  Don’t believe me?  Do this test, go outside and shot a picture and shoot it in jpeg and then shoot it in RAW.  Download the two pictures and compare the file size of the jpeg with that of the image shot in RAW.  You should note a huge difference in the number of megapixels which make up each image.  The RAW file, depending on your camera, can be twice as big as the jpeg file.  So what happened to all those megapixels?  The camera post processed the jpeg image based on the camera’s internal stored memory data and then discarded all the pixels it did not use.  Threw them away not be seen again, co-poof, gone.  No chance of ever recovering detail in post processing.  Did you know that the discorded data could be up to 61% of the total that could have been captured?  The next images were taken with a Nikon 24megapixel camera, Nikon D750. (Click on an image to enlarge it.)
The above image was captured as a jpeg right out of the camera and consisting of 11.92MB and at a resolution of 300ppi.   When you compare this to the image below (Image II) it is obvious that the camera has applied some processing.  The RAW file below is muted or dull and flat in appearance. (Click on an image to enlarge it.)
This second image is the unprocessed RAW file and contains 28MB of data, just waiting to be processed.  Note the difference in the sizes of the two images, 11.92MB for the jpeg and 28MB for the RAW file.  That is a loss of data of approximately 57%, this will differ with various cameras but the principal will always be the same.  What happens to that data?  It is lost.

So what is so important about this?  The ability to recover highlights and shadows in post processing is lost.  Many times, as I will show later in this article, data can be recovered in processing.  Today’s cameras have the ability to record a large amount of dynamic contrast, the difference between lights and dark, which can be brought forward in the digital darkroom (computer).

Let’s look at image III taken with a Nikon 36megapixel camera, Nikon D810. Even though I used two different cameras from different periods in time the principal of lost data from shooting jpeg versus RAW is the same. Just for information this was captured at Millstream Gardens on the St. Francis River.  This RAW file is 76MB in size.  The jpeg version of this image would be about 29MB or 61% less data.  Note here that the sky appears to be washed out or overcast.  However, on the day this picture was taken there were in fact clouds in the sky.  But standing in the shade and shooting a scene that has a bright sunny background is definitely a high contrast scenario.  But like I said today’s cameras can capture a large range of light/dark contrast. (Click on an image to enlarge it.)


So I am going to take this image into Photoshop and process it to bring back the details not showing but were in fact captured by the camera.  How can I do this? Because the data is still there in the RAW file, it was not discarded by the camera but in fact was captured and stored on the SD card.  This affords me the opportunity to recover as much data in the image as is possible.  I usually begin with some general adjustments in a RAW processer.  My RAW converter is “Adobe Bridge”. I use it to set the camera mode, correct for “Chromatic Aberration” should any exist and enable “Profile Correction”.  I use Layers in Photoshop to pull back the light and open up the shadwows but this can be done in “Bridge” or “Lightroom”.

Before we go any farther lets explain Chromatic Aberration and Profile Correction.  Chromatic aberration (also known as color fringing or dispersion) is a common problem in lenses which occurs when colors are incorrectly refracted (bent) by the lens, resulting in a mismatch at the focal point where the colors do not combine as they should. 
It can appear as a green or red fringe around the sharp edges of your subject.  Chromatic Aberration happens because your lens acts as a prism; bending light depending on the various properties of the glass.

Profile correction allows you to fix lens problems such as distortion, chromatic aberration, and vignetting.

There is a lot that can be down in the “Bridge” or “Lighroom” and for general purposes you should be able to accomplish everything you need in these programs.  You can adjust the temperature, to make your image cooler or warmer.  Adjust contrast locally or globally.  Pull back the highlights in case there is some spiking of them and open up the shadows.  Adjusting clarity can make a picture appear to be sharper and you can even apply sharpening and reduce noise as well.  You can also adjust the saturation of colors globally or increase non-saturated colors by adjusting the vibrance slider.

Image IV is the completed processing of the RAW file.  Not that I was able to recover some really nice clouds, opened up some mid-tones or shadows, brought out the colors, and increased the overall sharpness, all without distorting any parts of the image.  Because of the file size I could enlarge this picture for printing without any loss of detail. (Click on an image to enlarge it.)


I should point out that shooting in RAW will require more processing time and this can be daunting if you have taken hundreds of shots.  Today’s software’s make it possible to process one image and then copy the adjustments to subsequent images.  There are hundreds of presets available to aid in the processing task as well as plug-ins like NIK and Topaz or even On1.

I shoot in RAW but there are times when jpeg is the way to go.  For example when I shoot a sports event like a high school football game I will shoot in jpeg.  I have even been known to shoot wildlife in jpeg and RAW at the same time.  Now there is absolutely nothing wrong with whichever method you prefer and with cameras offering 36 to 50 megapixels there is a lot of room for adjustments even in a jpeg file.  I have seen some drop dead gorgeous landscape images that were taken in jpeg mode.  But to capture that breathtaking sunset or sunrise or any dynamic range landscape I encourage you to shoot in RAW format.  Beside for me post processing can be as much fun as actually taking the image.  Well maybe the next best thing to taking the image.