Rawnalyze

The dialog

Dialog elements

Resizing the dialog window

Magnifying, reducing the image size

Scrolling, positioning the image

Working with the sliders

Changing the original raw data

Pixel selection

Area selection

Dialog elements

After starting Rawnalyze, following dialog window appears:

The capture has been created in the initial state

The first step after having started the program is usually locating the raw file and opening it. The file specification can be typed in directly; clicking on Process starts opening and reading the file. However, more often the Browse subdialog will be used to select the raw file to process. After a file has been selected, it will be opened and read immediately, there is no need to click on the Process button; in fact, there is no need to click on Process any more while analyzing the same raw image. The only exception is, when switching between analyzing modified and unmodified raw data, see Changing the original raw data later. Clicking on Process initiates opening and reading the raw file again, causing a considerable delay in response time.

The shortcut for starting the file browse dialog is Ctrl-O.

Displaying the manual through a Web browser via the Help function may become necessary, but if someone is reading this page, then that goal has been accompished already.

As there is not much else to say about this screen shot, let's skip ahead through opening an actual raw file.

Resizing the dialog window (click to display this section)

Magnifying, reducing the image size (click to display this section)

Scrolling, positioning the image

• The easiest way of moving the image in the window is to drag it by the mouse by left-clicking anywhere on the display area, holding the mouse button down and moving the mouse.
• The most obvious way of scrolling is via the scroll bars. As customary in Windows, the scroll bar can be dragged, clicked above or below, the end arrows can be clicked on, etc.
• As long as a scroll bar is active (after having clicked on it and the bar is blinking), following keyboard actions are inducing scrolling,
  • PageUp and PageDown change the position by the size of the displayed image segment,
  • Home positions to the top left corner of the image,
  • End positions to the bottom right corner of the image.

  As long as the mouse pointer is not over the display area (while a scroll bat is active):

  • both CursorUp and CursorLeft move the window over the image to the left respectively up by the width/height of one CFA pattern (two pixels in normal size view, one pixel in reduced size view). The direction of movement depends on which scroll bar is active,
  • both CursorDown and CursorRight move the window over the image to the right respectively down by the width/height of one CFA pattern (two pixels in normal size view, one pixel in reduced size view). Again, the direction of movement depends on which scroll bar is active.

    This way a precise position can be established.

• While the mouse pointer is over the display area, even if a scroll bar is active:
  • CursorUp, CursorDown, CursorLeft and CursorRight move the window over the image by one half of the respective page size upwards, downwards, to the left or to the right, respectively.
  • the same keys move the window to the top, bottom, left or right end, respectively, if the Ctrl key is pressed as well,
  • the same keys move the window by a full page if the Shift key is pressed as well.
• At any time, when the Ctrl key is pressed:
  • the PageUp and PageDown keys position to the top respectively to the bottom, without changing the horizontal position,
  • the Home key positions to the top left corner of the image,
  • the End key positions to the bottom right corner of the image.

Working with the sliders

While the focus is on a slider, it can be moved just like a scroll bar, using the arrow keys, PageUp, PageDown, Home and End. The magnitude of change the arrow keys or PageUp and PageDown cause depends on the slider.

The slider becomes focused after having clicked on any part of it, and it remains focused until clicking on another control (a button, an input field, etc.) If the slider is focused, it is framed by a thin dotted rectangle, like this one:

Each sliders is accompanied by a Reset button, which sets the slider to its initial position.

There are other, very special ways to control the black point and white point values, and thereby the respective sliders; those are described in the Pixel selection.

Changing the original raw data

Following options are available:

• replacing some low-order bits of the pixel values by nulls. This will be accomplished by holding down the Ctrl key and one of the numeric keys from 1 to 8. the latter specifying the number of bits to replace,

  Black level correction becomes somewhat inaccurate through this change, although changing only two-three bits from 14 does not make this noticable,

• shifting the raw value to the right (this corresponds to dividing it by 2 or 4 or 8, etc.). This will be accomplished by holding down both the Ctrl and the Shift key and one of the numeric keys from 1 to 8, the latter specifying the number of bits to shift.

  Black level corrections will be applied before this change and then reset to zero, so that it do not get applied later again. Also the white point and the histogram range will be adjusted.

The special key combination has to be kept pressed down when clicking on the Process button or when starting processing of a raw file in the Browse dialog. It's enough to keep these keys pressed one or two seconds long.

Note, that

• when referencing to the original pixel value in other chapter, always the modified value is meant, if it applies,
• the raw file will not be changed by these manipulations.

Pixel selection

When displaying the image in normal size, a rectangular area of the display can be selected by right-clicking at a point of the display, holding down the right mouse button and dragging the selection in the direction and to the size needed. The selected area is marked by an orange rectangle. Another selection can be made at any time; the previous selection will be released. The selection can be removed by the keyboard action Ctrl-D.

An important aspect of the raw pixel analysis is determining, which pixels should be involved in it and how. The selection is based on the color and value of raw pixels.

The effect of pixel color and value selection is described in other chapters, here we deal only with the way the selection occurs.

The tools of pixel selection are:

• the Black point and the White point values together determine the pixel value range, the black point giving the lower limit and the white point the upper limit of the range.

  The current values are shown in the respective input field. The range of possible values for both limits is

  • 0 to 16383 if the raw values are limited to 4095,
  • 0 to 65535 if the raw values are limited to 16383,
  • 0 to 131071 otherwise (this occurs with 16 bit depth, created by some digital backs).

  The initial value of the black point is either

  • the minimum of the black level correction values, if there are any; these are gained either from the descriptive data of the raw file, or calculated the so-called masked pixels around the image,
  • 0 if black level correction does not apply.

  (il s'agit des valeurs dans les champs éditables, commandés par les deux curseurs sur leur gauche. Les nombres dans les champs "statistiques" sont discutés plus loin)

  The initial value of the white point is either

  • the highest of the saturation/non-linearity levels of the pixels, if available,
  • the white level specification from the descriptive data of the raw file,
  • the maximum possible pixel value according to the bit depth of the sensor.

  The black point and white point can be set to the same value, thereby limiting the range to a single pixel value. The black point can not be higher than the white point. Selecting a higher value for black point than the current white point is, or a lower value for white point than the current black point is results in changing the other limit as well to the same value.

  As the pixel value limits need to be adjusted very often, sometimes with small changes, sometimes faster, a multitude of adjustment options are available. The values can be changed by

  • positioning the slider (the value in the input field reflects the slider's position). The operation of the sliders is described above. Note, that the sliders have 100 different positions, and as a slider is moved, the program recalculates the display for every position in-between. This can be very time consuming, particularly when displaying histogram of the mapped data of very large images, like those from digital backs.
    The response time can be shortened by entering the value in the input field or by switching to displaying the raw histogram,
  • by the respective Reset button, which reinstates the initial value,
  • by entering a value directly in the input field. The entered value can be activated
    • by pressing the Enter key.
      Note, that the focus remains in the input field, allowing for consecutive changes without having to click on the field again and again. The downside of this behaviour is, that one has to click twice on any other button, etc. when the focus was in one of the pixel value input fields, because the first click outside the input field finishes editing of that field, and another click is required to establish the focus elsewhere,
    • by pressing the Tab key, which then passes the focus to the other field (to black point if Tab is typed in the white point field and vice verse). This is an easy way to change the values of both fields.
  • by keyboard shortcuts in the input field. This is a special way of adjusting the values; the focus has to be on the respective input field and the adjustments can be carried out repeatedly, for example stepping through a range of pixel values. The statistics will be updated only if the Enter key is pressed in between.

    The special controls are:

    • CursorUp increases the current value by one,
    • CursorDown decreases the current value by one,
    • CursorUp with Shift increases the current value by five,
    • CursorDown with Shift decreases the current value by five,
    • CursorUp with Ctrl increases the current value by 10,
    • CursorDown with Ctrl decreases the current value by 10,
    • CursorUp with Shift and Ctrl increases the current value by 50,
    • CursorDown with Shift and Ctrl decreases the current value by 50.
    • CursorUp with Alt and Ctrl increases the current value by 500,
    • CursorDown with Alt and Ctrl decreases the current value by 500.

    All the above actions change the other limit as well, if required, to maintain that the black point is never higher than the white point.

    Following actions always change both limits together from their actual value, no matter if the focus is in the black point or white point input field:

    • CursorRight increases both current values by one,
    • CursorLeft decreases both current values by one,
    • CursorRight with Shift increases both current values by five,
    • CursorLeft with Shift decreases both current values by five,
    • CursorRight with Ctrl increases both current values by 10,
    • CursorLeft with Ctrl decreases both current values by 10,
    • CursorRight with Shift and Ctrl increases both current values by 50,
    • CursorLeft with Shift and Ctrl decreases both current values by 50.
    • CursorRight with Alt and Ctrl increases both current values by 500,
    • CursorLeft with Alt and Ctrl decreases both current values by 500.

    When reaching the lower or upper limit of specifications, it can occur that only one of the values get changed.

• Inclusion/exclusion from the pixel value range by means of the Outside range selection.
  When unchecked, pixels within the limits are selected, i.e. with values such as
          black point ≤ value &le white point
  When checked, selected pixels lie outside the limits, i.e. their values are such as
          black point ≥ value   OR   value ≥ white point

  The statistics will be changed when checking or unchecking Outside range, reflecting the changed selection. The sum of the pixel counts in inside and outside mode is not necessarily the total number of the pixels with the respective color, because pixels with values matching a limiting value are counted both inside and outside.

  This option can be checked or unchecked only in exposure display mode, therefor it may be necessary to change to exposure display mode in order to check or uncheck Outside range and change back to the other display mode, so that the statistics are adjusted according to this option.

• Pixel statistics

  The numbers under the color selection checkboxes in the black point and white point cntrol group reflect the number of pixels in the respective group, determined by the actual black point and white point values and by the inclusion/exclusion selection. The proportion of the selected pixels too is displayed, related to the total number of pixels of the particular color in the related group.

  The pixel statistics values are not updated after certain selection adjustments, in order to shorten the response time. In such cases the statistics is not shown; typing Enter causes the statistics recalculated and displayed.

  ??? Pas clair du tout. Les statistiques dans le bloc black point ne tiennent aucun compte du white point choisi (et réciproquement). Les valeurs dans le bloc white point sont toujours très basses, quelle que soit le white point choisi. Par contre, les nombres dans le bloc black point ont l'air de pouvoir varier entre 0 et le maximum de pixels possible dans l'image

• Color selection
  In the exposure and channel related display modes any of the three colors can be included in or excluded by checking respectively unchecking the R, G and/or B checkbox.

  Both the black point and the white point control groups contain a checkbox for each color. In channel related display mode a color is selected if at least one of the respective boxes are selected (i.e. either in the black point control group or in the white point control group).

  In exposure display mode the selection is more complicated. If Outside range is unchecked, then

  • the checkbox in the black point group controls the selection of pixels with values greater than or equal to the black point and less than 2048,
  • the checkbox in the white point group controls the selection of pixels with values greater than 2047 and less than or equal to the white point.

  If Outside range is checked, then

  • the checkbox in the black point group controls the selection of pixels with values lower than or equal to the black point,
  • the checkbox in the white point group controls the selection of pixels with values greater than or equal to the white point.

  The statistics shown in the black point and white point control groups are not affected by the color selections. However, the distribution of the values between the black point and white point control groups reflects the separation of "black" and "white" (or "lower" and "upper") range.

Area selection

The unit of selection is the color filter array pattern, i.e. a block of 2x2 pixels, not individual pixels. Thus a single pixel can not be selected.

The selection remains active between different display modes. When changing to histogram mode or to reduced size display, the selection remains defined but not displayed, nor is the related statistics displayed. When changing back to normal size display or to image or exposure display mode from histogram display, the selection will be shown again with the related statistics.

It is important to understand, that a part of the display area is selected, not a part of the image. When the image position is changed, the selection remains on the very same place, i.e. another part of the image gets selected, and the statistics is recalculated.

The selection remains unchanged even when opening another image; this is useful when comparing two images of the same scenery.

The use of a selection is:

• establishing white balance based on the selection; the keyboard action is Ctrl-W,
• displaying a small statistics relating to the pixels in the selected area,

Following screen capture helps explaining the display associated with a selection:

The orange colored rectangle frames the selected area;
the red rectangles mark the associated information.
The red markings do not appear on the dialog window,
they are drawn only for the sake of explanation.

• The block at the left side contains the co-ordinates and dimensions of the selected area:

  The numbers in the top row, between brackets show the position of the selected area in the entire image; the first number is the horizontal position from 0, the second one is the vertical position from 0. The co-ordinates are always even numbers, because the selection occurs in units of 2x2 pixel blocks.

  The bottom row contains the size of the area in pixels, width by height; these too are always even numbers.

  Note, that when the image position changes, the co-ordinates of the selected area change accordingly.

• The two long rows of numbers are the pixel statistics relating to the selected area:

  

  The data in the first row relates to the raw pixel values. There are three groups of data, relating to the red, green and blue pixels, respectively. Each group contains four numbers:

  • the lowest pixel value,
  • the highest pixel value,
  • the average pixel value; this is not the average of the lowest and highest value, but of all pixels of the respective color in the selection,
  • the standard deviation.
  • there is a fifth number for "AI", i.e. Average Intensity (see note below)

  I think a short explanation may be useful regarding the "intensity".
  
  What is the intensity of a certain patch in the raw image, how can it be measured and expressed? The brightness (the RGB values) is useless for this purpose: it depends on adjustments, on WB and on the mapping. The pixel values or their averages? They are useful only within a single image, but even so they can serve only to determine, which area was higher or lower exposed, but they do not necessarily reflect the proportions between the intensities.
  
  The problem with the pixel values is, that they are not so absolute as one would think of plain numbers. Think of 12bit and 14bit depth - 4095 is the greatest number with 12bit, but is is quite low with 14bit - and this is not all. Many cameras do not utilize the entire numerical range of the bit depth, and/or the lowest meaningful pixel value is not 0. Example: the Canon 40D's meaningful pixel values start at around 1000 and clipping occurs at 12740, 13820, 16220 or 16383, depending on the ISO. Or think of the Nikon D300, D3, D700, D3X: the user can select between 12bit and 14bit raw data.
  
  Accordingly, the intensity represented by a given pixel value can be evaluated only after removing these variables. The AI value represents the result of this evaluation, measured from the current clipping point downwards. For example if the average pixel value is half as much as the pixel value range in the given image, then the intensity is one EV down from clipping; this will be expressed as -1.00 EV.

  The data in the second row reflects the RGB values, as the pixels appear on the display:

  • the lowest RGB pixel value,
  • the highest RGB pixel value (the maximum is 255),
  • the average pixel value; this is not the average of the lowest and highest value, but of all pixels of the respective color in the selection,
  • the standard deviation.

  The RGB values depend, beside on the raw values, on clipping indication, black point, white point, lightness correction, white balance and the mapping function. Changing any of these settings will be immediately reflected in the selection statistics. Likewise, the effect of changing the image position (scrolling, moving the image around) becomes immediately visible in the statistics.