Default projection assumes projection dimension interval starts at 0

@gselzer

The DimensionIterable class in DefaultProjectParallel (see below) does not project any data from negative coordinates in the projection dimension, basically assuming that the RAI has a zero valued origin. This causes the projection to be incomplete if the data spans into negative coordinates. In line 109, k is statically set to -1, when it should probably be set to the min value for that dimension. I think this would require another parameter (starting position?), and passing it a value of input.min(dim), then subtracting 1 from that. Luckily this is a nested class and this change doesn't seem like it should affect the Op call.

This issue also seems to be present in ImageJ ops, but I know we're not updating that any more.

scijava/scijava-ops-image/src/main/java/org/scijava/ops/image/transform/project/project/DefaultProjectParallel.java

Lines 91 to 129 in 82d58a2

    
           final class DimensionIterable implements Iterable<T> { 
        
           	private final long size; 
        
           	private final int dim; 
        
           	private final RandomAccess<T> access; 
        
           	public DimensionIterable(final long size, final int dim, 
        
           		final RandomAccess<T> access) 
        
           	{ 
        
           		this.size = size; 
        
           		this.dim = dim; 
        
           		this.access = access; 
        
           	} 
        
           	@Override 
        
           	public Iterator<T> iterator() { 
        
           		return new Iterator<T>() { 
        
           			int k = -1; 
        
           			@Override 
        
           			public boolean hasNext() { 
        
           				return k < size - 1; 
        
           			} 
        
           			@Override 
        
           			public T next() { 
        
           				k++; 
        
           				access.setPosition(k, dim); 
        
           				return access.get(); 
        
           			} 
        
           			@Override 
        
           			public void remove() { 
        
           				throw new UnsupportedOperationException("Not supported"); 
        
           			} 
        
           		}; 
        
           	} 
        
           }

@andmccall

@andmccall great catch, yet another bug in these projection Ops 🙁

I think that fixing these projection Ops is quickly jumping to the top of my SciJava Ops priority list.

This issue also seems to be present in ImageJ ops, but I know we're not updating that any more.

To be clear, bugfixes to ImageJ Ops are always welcome - I just don't want to add new Ops 😅

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Default projection assumes projection dimension interval starts at 0 #292

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	final class DimensionIterable implements Iterable<T> {

	private final long size;
	private final int dim;
	private final RandomAccess<T> access;

	public DimensionIterable(final long size, final int dim,
	final RandomAccess<T> access)
	{
	this.size = size;
	this.dim = dim;
	this.access = access;
	}

	@Override
	public Iterator<T> iterator() {
	return new Iterator<T>() {

	int k = -1;

	@Override
	public boolean hasNext() {
	return k < size - 1;
	}

	@Override
	public T next() {
	k++;
	access.setPosition(k, dim);
	return access.get();
	}

	@Override
	public void remove() {
	throw new UnsupportedOperationException("Not supported");
	}
	};
	}
	}

Default projection assumes projection dimension interval starts at 0 #292

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gselzer commented on Aug 12, 2026

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