Instructions

(last update11/03/2006 )

& Didier Leboutte

Tutorials

See the list here.

Old user guide

Be careful : the following explanations are for the old windows-only version. Major features are also common to the new java version, but you can find few differences here or there. Particularly, the stereo-morphing is specifique to the old windows version. The new Java version offers a new experimental tool : see 2D->3D->Stereo Sculptor

PDF version

Thanks to Quang Vo for this PDF conversion of this guide !

Anaglyph

To see depth each eye needs a different image, corresponding to the shifted position of the eyes at the time of observation ( about 6 cm)  An anaglyph is an image obtained by the superposition of these 2 images in complementary colors, for example Red and Cyan.  By looking at this image with a Red/Cyan glasses, the left eye sees the Red image (original left), while the right eye sees the Cyan (original right) image.  The brain recomposes the full colors and gives the impression to see an image having all the colors the originals... and with depht !
Lunettes Anaglyphes

That goes very well for all the colors which are not too close to the Red or the Cyan.  Because if not, there is only one eye which sees the part of the image of this color : a bush of roses with red flowers does not look very well in Anaglyph.  In this case, the automatic function of desaturation of reds and cyans of AnaBuilder will enable you to correct the colours so as to make the Anaglyph observable : the flowers will not be red any more, but they will be visible in the colour of your choice (violets, yellows, black.. pink?).

It should not be forgotten that 3D photography, is above all photography.  So, AnaBuilder integrates some basic functions which will enable you to improve the quality of the result.  Some of these functions have a direct influence on the quality of the 3D perception (as the filter of vertical edges improvement), others make it possible to catch up with certain errors made during photoshooting : luminosity, colors, etc...
Learn to use them sparingly, because nothing will replace good shots.

If one does not have a camera with 2 objectives, it is only possible to photograph motionless subjects.  Even a minimal displacement of the subject completely distorts the 3D result. But with a camera with 2 objectives, it is possible to shoot in 3D all the drops in suspension of a fountain (splendid!).

Photographs

Take 2 shifted photographs :
Prendre 2 photos

The ideal is to have a camera (numeric) that can take photographs in burst.  It should be used without flash to avoid having to wait during recharging.  Launch the catch in burst and move the apparatus from left to right to make a series.  Take a stronger sensitivity (or numerical equivalent) to avoid blurring. AnaBuilder then makes it possible to test in a very flexible way the combinations of photographs, to find the best suited pair.

Important : if a picture is taken with a flash on the camera, the shade moves with its position, and will not caught in 3D.  It is the case of my clown, but I did not know it when I took the pictures. Note the displacement of the shade of the flowers on the hip.

Example :

Photo gauche
Left
Photo droite
Right

First assembly

Launch AnaBuilder :
Ecran de départ

Load the left image, then the right. The composit Red/Cyan image should appear. Resize the window to have the good proportion.  The larger the image, the easier precise retouching, but more time will be spend during processing of the changes. It is possible to adapt the width and/or height of the image to allow easier correcting.

Premier Anaglyphe


To optain optimal depth, the 2 images must overlap as complete as possible.

Horizontal and vertical fitting

Choose an object of the image, about in the center of the image, which will have to appear at the depth of the screen in the 3D image (neither in front, nor behind). This reference  object will be used during the whole assembly process.

Example :  the large button of the sweater of the clown.

Click on the image with the left button of the mouse. Keeping the button pressed, shift the Cyan image to superimpose the reference object as good as possible :
Premier ajustement

Click on "Diff" at the top left. The difference image can be used to finetune the shifting process. All well fitted parts of the image become black, and the shifted are colored.But keep in mind that, as the images are different, coloured zones will appear inevitably: some are due to a bad fit, and others due to the 3d (perspective) shift.
Image différence

Use the buttons on the left side, to make the reference object as black as possible. You can alternatively pass from the color image to the difference image to refine the result.

Rotational fitting

An object seen the 2 images (left,right) can show horizontal shift between its red and cyan components depending on its position relative to the reference object which has just been adjusted. but they should not present vertical shifts !!. Therefore horizontal edges of objects should not show color( red/cyan) shifts:
  1. On the color image, there should not appear Red or Cyan shift on horizontal edges.
  2. On the difference image, horizontal edges must disappear to become completely black.
Locate a horizontal edge on the right of the image and an other on the left of the image to locate a possible rotation defect. Use the rotation buttons on the left to eliminate the rotation defects. If need, refit the image horizontally or vertically as explained before (using the reference object).
Calage en rotation

Expansion Adjustment fit

Find an horizontal edge on the top of the image, and one other on the bottom, to find a possible size defect. As for the rotational fitting, use the enlargement and contraction buttons to eliminate the homothety defects. If required, refit the image horizontally or vertically as previously, using the the reference object (or any other one if that is easier).
Calage en homothetie

Finalisation

Put the Red/Cyan glasses on. When the fitting is successful, the image should seem to exist in space, and the presence of the 2d screen should not be noted. Do not forget that it is best to look at the image in its original proportions so, save the image en reopen it fullscreen in a dedecated imageviewer program.

For a good appreciation, wait a few seconds so that your eyes get accustomed to the anaglyph.
 
The larger the distance to the screen, the easier for the eyes to focus and to deduce the depth. Therefore, if initially you find it hard to see the depth, move away from the screen to 2 or 3 m, and gradually get closer again.

It is possible to accentuate the position of objects behind the screen by moving the Cyan image to the left. On the other hand, it is possible to accentuate the position of objects in front by moving the Cyan image to the right. If the rotation and dilatation fits are successful, the eyes accept a rather important left/right displacement. If not, the observation quickly becomes unpleasant, and the image loses of its depth.

You can make an object 'jump' out of the screen, by shifting the cyan part of the image but care should be taken not to let object touch the border of the screen. The eye locates very well the borders of the image at the distance corresponding to the screen. The interaction of an object thought to be in front of the screen with the border of the image breaks completely the depth impression. This is true for the top and bottom borders, but that is even more for the left and right borders. To have an object on the front of the screen, one needs an important left/right shift between the 2 images. Because of this shift, one of the 2 images finishes inevitably earlier on the border than the other. There is thus a piece of image which will be seen only by one eye, which breaks the stereoscopic effect.

Color Filtres

Luminosity : value between -255 and +255, the value with no effect is 0

For a positive value: this filter shifts all colors in the same way to the white. The palest colors are saturated to the white. The blacks become grays.
For a negative value : this filter shifts all colors in the same way to the black. The darkest colors are saturated to the black. The whites become grays.

Contrast : value between 0 and +255, the value with no effect is 1

For a value > 1 : this filter dilates the color histogram from the center to the extremities. The palest colors are saturated to the white. The darkest colors are saturated to the black.
For a value < 1 : this filter compresses the color histogram from the extremities to the center. The whites become grays. The blacks become grays.

Gamma : values between 0 and +255, the value with no effect is 1 (an increment corrects the global value for each RGB component)

For a value > 1 : this filter shifts all colors to the white. The whites and blacks are preserved.
For a value < 1 : this filter shifts all colors to the black. The whites and blacks are preserved.

White balance : values between 0 and +255, the values with no effect are +255

The 3 RGB components are rescaled to set the white color to the indicated value. The blacks stay blacks. The colors paler than the one indicated become white.

L/R exposure correction : values between 0 and +255, the value with no effect is 1

The 3 RGB components of the right image are rescaled in order to make the global luminosity identical to the left image. The blacks are preserved. The palest colors become either whiter or darker, according to the sense of the correction. The "auto" button calculates this value.

If the two views are not of the same luminosity, it gives a red shift, and on the contrary a cyan shift :
Plus sombre
Normal
Plus Cyan
The left view is darker. The anaglyph shifts to cyan.

Plus lumineux
Normal
Plus Rouge
The left view is less dark. The anaglyph shifts to red.

Shift R/G at right :

This transformation changes reds to yellows in the right image to avoid flashing on the anaglyph. This transformation is not always possible, for esthetics reasons, but may produce good results in certain cases.

See for example the images produced by Didier Leboutte using this technique for his aeroplanes and helicopters .

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