Is there an quivelent to Photoshop's 'Auto Levels' and/or 'Equalize'?

Or to put it another way, is there a way to get the curve of the external image?

Guess this should be moved to feature wishlist Vlad?

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uberzev wrote: Guess this should be moved to feature wishlist Vlad?

I'm afraid that it can't be done. Here's why:

For auto-levels, you need a histogram. To build a histogram, you need the whole image. The problem is that Filter Forge doesn't operate on whole images, it operates on blocks (the squares you see in the preview when it renders the picture). A histogram of a single block is useless for auto-levels, you need the whole picture.

Even if Filter Forge had a way to calculate a histogram of an entire image, filters that use this would be painfully slow and completely non-interactive -- you wouldn't see anything in the preview until the histogram is rendered.

So, to my regret, the current architechture of Filter Forge does not allow histograms and therefore auto-levels to be implemented.

Block size is dynamic and is dependent on different factors, including output image size (with discrete steps and certain alignments) so you won't fit your tile into a single block reliably.

Actually, the rough histogram estimation is possible if the histogram source in question is sampled with a decreased resolution. But even if this hypothetic Histogram (or MinMax or whatever) component is implemented, it's actual performance hit on the filter rendering is indeterministic and so it should not be allowed.

The only exception to this rule would be a histogram of the input image. For stand-alone mode we are able to determine the input image histogram (or at least min/max/median/whatever) at zero additional cost. On the other hand, the plugin mode will suffer some serious penalties for large images, since, unfortunately, hosts (i.e. Photoshop) do not make their histogram caches available to the plugins The performance penalty is probably not that high though, especially for images with dimensions below 2048x2048, and if the histogram downsampling is allowed, certain hosts that fully implement the plugin interface (most of Adobe hosts) may provide us with moderately fast histogram retreival.

To summarize -- stand-alone mode min/max/median and other single-value curve data is relatively easy, plugin mode isn't.

Hmmm... I have to admit that the idea is interesting. We'll explore that on low priority.

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Bongo51 wrote: Any sort of accurate 'obtain highest lum value' or lowest etc. would be a big assistance.

We had a discussion about this feature yesterday. The current status is as follows:

We still can't do any histogram-based operation that takes an unbounded procedural component as a source simply because components never gets to see the "whole image" (see my and onyXMaster's explanations above).

However, onyXMaster's idea about offering histogram-based data for the input image and selection (represented by External > Image and External > Selection components) seems to be well within the practical bounds. This may lead to some overhead (as he explained above), but this isn't a showstopper.

As for the implementation, we're going to explore this idea together with the unclipped HDR pipeline and HDR math components -- these things are closely related.

I've been toying with these new components myself lately and haven't figured out how they are used.

Anyone have an example I can look at?

Still looking for an equalize filter. Perhaps this could be a custom script?

...and looks like making an equalize filter is pretty easy from there.

Question: what exactly is the filter doing?

Group Component version.

Equalize Group.ffxml