Image Combining - tone-mapping MIFF doubt

[markmarques]

I am using Windows and Imagemagick 6.6.7 manually compiled with HDRI ....

My problem is this :

I am trying to "combine" 3 images (keeping the maximum quality for each hence the MIFF format idea) in single script ...

Resuming the idea :
From a single RAW photo it is possible to achieve greater dynamic range if processed into 3 distinct "EV" exposures...
Something like -1EV, 0EV, +1EV combined ...
My idea would be using the HDRI + MIFF options in order not loose any info ...

My problem is that the "usage example" is very simple regarding the MIFF usage ...

I do have a DOS batch script in order to create each exposure and then combine them into the final image ...
But my idea ide would be to pipeline them in order to avoid the 3 extra files ...

for what I have read with MIFF example each time the MIFF: is called it appends an image to the previous one ... (right?)
But how can I access for instance the 3rd image ?
Or am I thinking wrong in this case ?

I have something like :

FOR %%G IN (1,3, 17,23 ) DO convert %1 -sigmoidal-contrast %%G,0%% -auto-level miff:ab_%%G.miff
convert ab_1.miff ab_3.miff ab_17.miff ab_23.miff -evaluate-sequence mean Finalimage.jpg

Is there any way to avoid creating the 4 "temp MIFF" images ?
Or there any way to give each image a weight ?
where can I find more info regarding the "convert -list evaluate " command option ...

[fmw42]

I am not a windows user and don't know Batch processing for windows. But if you just have 4 things to compute, you can do each within a parenthesis and then in the same command do the -evaluate-sequence. In unix, it should be something like this:

convert inputimage \
\( -clone 0 -sigmoidal-contrast 1,0% -auto-level \) \
\( -clone 0 -sigmoidal-contrast 3,0% -auto-level \) \
\( -clone 0 -sigmoidal-contrast 17,0% -auto-level \) \
\( -clone 0 -sigmoidal-contrast 23,0% -auto-level \) \
-delete 0 -evaluate-sequence mean resultimage

In Windows, you need to escape the % as %% and parenthesis don't need to be escaped with \ and the line continuation \ is replace with ^, if I am not mistaken. See http://www.imagemagick.org/Usage/windows/

[markmarques]

Initially I changed my script with several FOR s but it became so slow that I were about to discard it ....

Now with your answer it become clearer ....
It is about ten times faster ...

Now I have several new ideas ...

dumb question:
By using the clone option what is the "pixel quality" of the cloned data?
For instance if originallly I read an 8 bit GIF and applaied the clone what is the depth of the cloned image ? 8bit or quantum depth ?
or can I "force" a depth by calling the "depth X" option ?




Thanks for the answer ...

[anthony]

The pixel data of the clone is preserved (it is fast) when the data changes then a new pixel data cache is created.

IM does not 'lose' quality if you can help it. Typically the loss is forced on it by saving to a image file format.

See IM Examples, Basics, Depth and Quality
http://www.imagemagick.org/Usage/basics/#depth