fix(IBA): Handle offset data windows in fillholes_pushpull

Fixes 4942

IBA::fillholes_pushpull() produced incorrect result when the source
image had a non-zero data window origin (such as exr files with
overscan).

Two interrelated bugs:

1. The paste() call double-applied the data window offset. paste()
   maps source pixel (0,0) to destination (xbegin,ybegin), but since
   the source data starts at (x,y), passing (x,y) as the offset
   shifted every pixel by an extra (x,y). Pixels in the
   negative-coordinate region landed outside the destination buffer
   and were silently lost.

2. The top pyramid level preserved the original display/full window
   while all smaller levels had full=data at (0,0). Since resize()
   uses the full window for coordinate mapping, it only sampled the
   display window portion of the top level, losing all overscan data.

Fix by shifting the top pyramid level to origin (0,0) with full=data,
making all levels coordinate-consistent. The initial paste translates
source pixels into the origin-based pyramid, and the final paste
(which was already using src origin offsets) correctly translates
back.

Add test cases in testsuite/oiiotool for fillholes with an offset data
window, and an offset display window, to ensure that both cases work.

Also, for the existing fillholes related test, move the source image
from ref (never should have been there) to src.

Assisted-by: Claude Code / claude-opus-4-6

Signed-off-by: Larry Gritz <lg@larrygritz.com>

Author: lgritz

src/libOpenImageIO/imagebufalgo.cpp

@@ -1614,10 +1614,20 @@ ImageBufAlgo::fillholes_pushpull(ImageBuf& dst, const ImageBuf& src, ROI roi,
 
     // First, make a writable copy of the original image (converting
     // to float as a convenience) as the top level of the pyramid.
+    // Shift everything to origin (0,0) with full=data so that resize
+    // correctly maps the entire data extent between pyramid levels,
+    // even when the data window is offset from the display window.
     ImageSpec topspec = src.spec();
     topspec.set_format(TypeDesc::FLOAT);
-    ImageBuf* top = new ImageBuf(topspec);
-    paste(*top, topspec.x, topspec.y, topspec.z, 0, src);
+    topspec.full_x      = 0;
+    topspec.full_y      = 0;
+    topspec.full_width  = topspec.width;
+    topspec.full_height = topspec.height;
+    topspec.x           = 0;
+    topspec.y           = 0;
+    topspec.z           = 0;
+    ImageBuf* top       = new ImageBuf(topspec);
+    paste(*top, -src.spec().x, -src.spec().y, -src.spec().z, 0, src);
     pyramid.emplace_back(top);
 
     // Construct the rest of the pyramid by successive x/2 resizing and

testsuite/oiiotool/ref/data-offset-hole-filled.exr

@@ -126,6 +126,10 @@ Comparing "tahoe-filled.tif" and "ref/tahoe-filled.tif"
 PASS
 Comparing "growholes.tif" and "ref/growholes.tif"
 PASS
+Comparing "data-offset-hole-filled.exr" and "ref/data-offset-hole-filled.exr"
+PASS
+Comparing "display-offset-hole-filled.exr" and "ref/display-offset-hole-filled.exr"
+PASS
 Comparing "rangecompress.tif" and "ref/rangecompress.tif"
 PASS
 Comparing "rangeexpand.tif" and "ref/rangeexpand.tif"

testsuite/oiiotool/ref/display-offset-hole-filled.exr

@@ -121,9 +121,12 @@
                      + "--siappendall -trim -origin +0+0 -fullpixels -d uint8 -o trimemptysubimages.tif")
 
 # test hole filling
-command += oiiotool ("ref/hole.tif --fillholes -o tahoe-filled.tif")
+command += oiiotool ("src/hole.tif --fillholes -o tahoe-filled.tif")
 # test hole filling for a cropped image
 command += oiiotool ("-pattern checker 64x64+32+32 3 -ch R,G,B,A=1.0 -fullsize 128x128+0+0 --croptofull -fillholes -d uint8 -o growholes.tif")
+# test hole filling with offset data and data windows (issue #4942)
+command += oiiotool("--create 64x64-16-16 4 --fullsize 32x32+0+0 --box:color=1,0,0,1 0,0,31,31 --box:color=0,1,0,1 1,1,30,30 -d half -o data-offset-hole.exr --fillholes -o data-offset-hole-filled.exr")
+command += oiiotool("--create 64x64 4 --fullsize 32x32+16+16 --box:color=1,0,0,1 16,16,47,47 --box:color=0,1,0,1 17,17,46,46 -d half -o display-offset-hole.exr --fillholes -o display-offset-hole-filled.exr")
 
 # Test --min/--max
 command += oiiotool ("--pattern fill:top=0,0,0:bottom=1,1,1 64x64 3 "
@@ -285,6 +288,7 @@
             "abs.exr", "absdiff.exr", "absdiffc.exr",
             "chsum.tif",
             "tahoe-filled.tif", "growholes.tif",
+            "data-offset-hole-filled.exr", "display-offset-hole-filled.exr",
             "rangecompress.tif", "rangeexpand.tif",
             "rangecompress-luma.tif", "rangeexpand-luma.tif",
             "min.exr", "cmin1.exr", "cmin2.exr",

testsuite/oiiotool/ref/out.txt

@@ -532,7 +532,7 @@ def test_iba (func: Callable[..., oiio.ImageBuf], *args, **kwargs) -> oiio.Image
     bad.clear()
 
     # fillholes_pushpull
-    b = test_iba (ImageBufAlgo.fillholes_pushpull, ImageBuf(OIIO_TESTSUITE_ROOT+"/oiiotool/ref/hole.tif"))
+    b = test_iba (ImageBufAlgo.fillholes_pushpull, ImageBuf(OIIO_TESTSUITE_ROOT+"/oiiotool/src/hole.tif"))
     write (b, "tahoe-filled.tif", oiio.UINT8)
 
     # over