FastRawViewer Developers Blog

ISO is Seldom just a Digital Gain

RawDigger. Raw histogram. Digital ISO 25600

Some say, "exactly like dragging exposure slider in Lightroom, ISO ... is just digital gain". With a few exceptions, this is less than a half-truth.

Though it is often the case that at higher ISO settings digital "gain" is applied (or a converter, using a metadata tag, is instructed to apply it), analog gain still acts first, before "digital gain" (the better word would be "multiplication", not gain, as in electronics "gain" most often pertains to analog domain).

The giveaway for multiplication is deep and regular gaps in the raw histogram that become wider with each increase of ISO setting.

A Curious Case of ISO Bracketing with Fujifilm X-series

A few days ago, a FastRawViewer user turned to us with a question:

"I took a series of photos with ISO bracketing, but FastRawViewer shows them all in the same way on the main window, even though the JPEG previews are different. I think you have a bug!"

In answering him, we suggested several reasons as to why this is happening, among which was the option that "It's possible that your camera doesn't even do anything when the ISO is changed".

The user sent us the files, and the result was...exactly that; the automatic change of the ISO setting while bracketing didn't affect the RAW data at all.

Time for Standards, stockbakery

Red Flowers Photography: Real Problems or Deceptive Previews?

"...Images of red flowers sometimes don't come out very well, seeming oversaturated, and having little detail in certain areas.”

"...In some pictures of red flowers, I can see small white specs on the petals. On other shots, the entire flower appears flat, like one neon blob, lifeless and lacking volume; it can be quite disturbing."

"...When I'm shooting red flowers, I often have a problem: to save the red channel, I usually have to tell the camera to expose below what it considers to be the correct exposure. This results in overall underexposure in the rest of the scene..."

Maybe, the main problem is that the preview you see is not what you got?

FastRawViewer. Grid View. Red Flowers

Sorting Photos with FastRawViewer

So, the shoot is over and you need to deal with the material you got from it. There's always the allure of sorting photos, setting the ratings and labels directly to the memory card, moving photos to different folders and then just deleting what's unnecessary from the card.

However... writing to a memory card outside the camera is unsafe (USB malfunctions, sudden disconnects, card failure, spontaneous computer reboots - any or all of these may cause a disaster).

We are often asked, how do we deal with these limitations and risks ourselves? Now, we're not saying that this is the only way, but here is what we do: we follow 2-stage workflow for sorting photos, which avoids both writing to a card and wasting time and disk space on copying and ingesting (into Adobe Lightroom) all the files while some of them may be “missed shots”.

FastRawViewer. Sorting Photos

New Old Approach to Dynamic Range

In today's world, "dynamic range" (DR) has become, in the minds of (many) photographers one of the main characteristics of a digital camera.

Unfortunately, the public data on DR is limited to "DD - ISO sensitivity" graphs and tables. With this, the nature of noise (for example, random noise, banding) isn't accounted for, however the noise character is important for visual quality.

In reality, any practicing photographer knows that the degradation of the image in the shadows (or because of low exposure) happens gradually. With the lowering of exposure, small details disappear, the contrast between bigger details diminishes, color fidelity becomes worse. Depending on the quality demanded of the image (which will depend on presentation size, viewing distance, other viewing conditions such as screen resolution, etc.,), the practical dynamic range for the specific camera will be different, even for the same ISO setting.

Michal Bednarek (Niserin)

Lightroom, XMP, Windows, and Removable Storage

As Adobe Lightroom Windows users know, this application has been oppressive for users of removable media (disk drives, flash cards), imposing some limitations that puts image culling applications that produce XMP files (including FastRawViewer) in a bit of a bind. It's impossible to cull/rate/label files right on a flash card - they first need to be copied onto a local disk, XMPed, and then imported into Lightroom from there.

Aside from problems with flash cards, the same happens with removable USB disk drives. If Lightroom detects the disk as being removable, it wil neither read nor write XMP files from or to that location.

Since we're a bit overwhelmed with the questions regarding this problem, and the answer "that's just Lightroom" is both overly repetitive and not very satisfactory, we suggest the following lifehack.

One Way to Get Spot-On Exposure for Your Shots

Practically every day, one can see threads on photographic forums where members discuss the various different modes of automatic exposure, trying to find the right one. As a rule, these discussions result in the same question – what compensation to automatic metering ought one set to get consistently good exposure? It turns out that no autoexposure mode universally guarantees good out-of-box results.

We are going to demonstrate that one of the ways of getting good exposure is metering while using the in-camera spotmeter on the lightest part of the scene that needs to maintain full detail (white clouds, snow, etc.) and applying the appropriate compensation to the exposure recommended by the spotmeter.

The shot taken with  spotmeter exposure and +3 EV in-camera correction, opened and adjusted in FastRawViewer

Can you Evaluate Exposure Using the In-camera Histogram?

They say that "a histogram is a graphical representation of the pixels exposed in your image" or "when judging exposure, the primary areas of the histogram to be concerned with are the right and left edges".

We are going to demonstrate the following:

  • In-camera histograms don't really allow one to analyze the shadows and highlights zones of an image.
  • An in-camera histogram changes significantly with changes in the camera settings such as contrast, picture style, brightness, etc.

So, no. By no means can the in-camera histogram be used by a RAW shooter to evaluate exposure.

shot 2649 with and without WB

Do Not Let White Balance Throw You Off-Balance

White balance: does it or does it not affect RAW image data at all? Certainly it affects JPEG, but how and why?

We are going to demonstrate that setting the white balance in a camera has no effect on "normal" RAW data.

To do so, we took four shots under the same, fairly constant, light, varying only the white balance (WB) settings in the camera (and the number of roasted coffee beans on the skillet handle). You will see the "as shot" color differs dramatically between the shots, yet the RAW histograms of these shots are, for all practical purposes, will stay the same.

You can repeat this simple experiment yourself, and also check that changing the white balance setting does not affect the in-camera exposure metering readings.

White balance as per channel response ("exposure") correction

How to Trash a Good Shot in One Step...

Not sure how? It really is very simple - just rely on the JPEG histogram. The one on the back of your camera will do, or one derived from a JPEG by some viewer, or (sometimes) even by a RAW converter.

Many strongly colored objects - yellow, red, blue, pink, orange, purple, etc. are suffering from culling based on JPEG histograms.

FastRawViewer is the only culling tool that displays the true RAW histogram, which allows you to determine if the shot was exposed correctly.

So, if you don't want to trade your (technically) best shots for worse ones, start using RAW histograms for culling!

Yellow daffodils. RAW and RAW histogram

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