How to achieve those filter chaining with GPUImage framework?

Question

I\'m trying to chaining blended layer and filter it

(Origin -> Texture1(opacity 30%)/HardLight -> Texture2/SoftLight) => level(45, 0.95, 238) + satu

Answer 1

I see a couple of problems:

1) There's probably a typo chaining text1's filters:

[text1 addTarget:filter1]; // Opacity
[text1 addTarget:blendFilter1]; // HardLight Blend

should instead be

[text1 addTarget:filter1]; // Opacity
[filter1 addTarget:blendFilter1]; // HardLight Blend

2) You're chaining filters to text1 and text2 GPUImagePictures but forgot to process them:

// Processing
[origin processImage];
[text1 processImage];
[text2 processImage];

3) UIImage *output = [blendFilter2 imageFromCurrentlyProcessedOutput];

You should call imageFromCurrentlyProcessedOutput on the last filter of the chain which in your case is the group filter. I wouldn't necessary use the GPUImageFilterGroup here which is usually used to create filter subclasses that use existing filters, but instead I simply would chain the last 3 filters to blendFilter2 like this:

...
// Result => level + saturation + hue
[blendFilter2 addTarget:filter2];
[filter2 addTarget:filter3];
[filter3 addTarget:filter4];

// Processing
[origin processImage];
[text1 processImage];
[text2 processImage];

UIImage *output = [filter4 imageFromCurrentlyProcessedOutput];

The full chain would be:

[text1] -> [filter1] \ 
                      +->  [blend1]  \
            [origin] /                +-> [blend2] -> [filter2] -> [filter3] -> [filter4]
                             [text2] / 

EDIT:

Watch out with those integer divisions setting min and max here:

[filter2 setMin:45/255 gamma:0.95 max:238/255]; // 45, 0.95, 238

min and max are 0!

[filter2 setMin:45 / 255.0 gamma:0.95 max:238 / 255.0]; // 45, 0.95, 238