Exr crop fills with white pixel.

[tokejepsen]

Prerequisites

• I have written a descriptive issue title
• I have verified that I am using the latest version of ImageMagick
• I have searched open and closed issues to ensure it has not already been reported

Description

When converting to the DWAA compression for EXRs, any cropped pixels get filled with white.

Steps to Reproduce

Convert any cropped EXR to a DWAA compression with the following command:

magick convert input.exr -compress DWAA output.exr

I have attached an image which contains a cropped roto shape (from Nuke), and an image convert with the above command to DWAA compression.

exr_compression.zip

System Configuration

• ImageMagick version:

Version: ImageMagick 7.0.8-68 Q16 x64 2019-10-05 http://www.imagemagick.org
Copyright: Copyright (C) 1999-2018 ImageMagick Studio LLC
License: http://www.imagemagick.org/script/license.php
Visual C++: 180040629
Features: Cipher DPC Modules OpenCL OpenMP(2.0)
Delegates (built-in): bzlib cairo flif freetype gslib heic jng jp2 jpeg lcms lqr lzma openexr pangocairo png ps raw rsvg tiff webp xml zlib

• Environment (Operating system, version and so on):

Windows 10

• Additional information:

[fmw42]

When I list out all the possible Imagemagick compression types, it does not list DWAA. Perhaps that is why your command does not work?

convert -list compress
B44A
B44
BZip
DXT1
DXT3
DXT5
Fax
Group4
JBIG1
JBIG2
JPEG2000
JPEG
LosslessJPEG
Lossless
LZMA
LZW
None
Piz
Pxr24
RLE
RunlengthEncoded
WebP
ZipS
Zip
Zstd

[tokejepsen]

@fmw42 are you on the latest version?

magick convert -list compress
B44A
B44
BZip
DWAA
DWAB
DXT1
DXT3
DXT5
Fax
Group4
JBIG1
JBIG2
JPEG2000
JPEG
LosslessJPEG
Lossless
LZMA
LZW
None
Piz
Pxr24
RLE
RunlengthEncoded
WebP
ZipS
Zip
Zstd

Its a very recent addition ImageMagick/exr#1

[fmw42]

Yes, IM 6.9.10.68 and 7.0.8.68. But I listed above from IM 6. I see now that if I use IM 7 and list the compressions, it does list DWAA. Sorry about the confusion.

[tokejepsen]

Looks like its not just the DWAA compression. Converting any EXR that has a crop, ImageMagick will fill the cropped pixels with white.

[fmw42]

If you crop, try adding +repage after the crop to remove the virtual canvas geometry. Does that help?

[tokejepsen]

If you crop, try adding +repage after the crop to remove the virtual canvas geometry. Does that help?

Do you mean like the following? That still has the white pixel fill.

magick convert +repage C:\Users\admin\Desktop\zip_compression.exr C:\Users\admin\Desktop\zip_compression.jpeg

[fmw42]

Remove the convert and put the +repage after the crop.

magick image.exr -crop WxH+X+Y +repage cropped_image.png

+repage should not be needed for JPG output, which does not support virtual canvas. So if your output is JPG and you have cropped your image, the cropped out area should not show.

Post a link to an example exr image and the exact command line you are using.

This command works just fine for me:

magick doll_small.exr -crop 50x50+0+0% x.jpg

IM 7.0.8.68 Q16 Mac OSX Sierra.

Perhaps I misunderstand your issue. Please clarify where the crop is done. Your command shows no cropping!

[tokejepsen]

Perhaps I misunderstand your issue. Please clarify where the crop is done. Your command shows no cropping!

Yeah, I may not have been very clear. The exr is already cropped from Nuke with its autocrop feature. Here is an EXR cropped from Nuke;
cropped.zip

Using this command results in the cropped pixel to fill with white;

magick cropped.exr cropped.jpeg

Resulting output:

Expected output:

[fmw42]

Yes, Imagemagick is getting the wrong arguments for the size for the EXR image.

Here is what I get from EXIFTOOL:

exiftool -s -ee -g1 -u -n -D cropped.exr
---- ExifTool ----
    - ExifToolVersion                 : 10.51
---- System ----
    - FileName                        : cropped.exr
    - Directory                       : .
    - FileSize                        : 50893
    - FileModifyDate                  : 2019:10:17 12:11:10-07:00
    - FileAccessDate                  : 2019:10:21 13:07:06-07:00
    - FileInodeChangeDate             : 2019:10:21 13:06:13-07:00
    - FilePermissions                 : 755
---- File ----
    - FileType                        : EXR
    - FileTypeExtension               : EXR
    - MIMEType                        : image/x-exr
    - ImageWidth                      : 695
    - ImageHeight                     : 562
---- OpenEXR ----
    - EXRVersion                      : 2
    - Layout                          : 0
    - Channels                        : B half 1 1, G half 1 1, R half 1 1
    - Compression                     : 2
    - DataWindow                      : 650 24 1344 585
    - DisplayWindow                   : 0 0 1919 1079
    - LineOrder                       : 0
    - Nukefull_layer_names            : 0
    - Nukenode_hash                   : 48ff295dda5c5066
    - Nukeversion                     : 11.0v4
    - PixelAspectRatio                : 1
    - ScreenWindowCenter              : 0 0
    - ScreenWindowWidth               : 1
    - Type                            : scanlineimage
    - Version                         : 1
---- Composite ----
    - ImageSize                       : 695x562
    - Megapixels                      : 0.39059

Note the ImageSize parameter near the bottom as 695x562. But Imagemagick is using:

cropped.exr
Image: cropped.exr
  Format: EXR (High Dynamic-range (HDR))
  Class: DirectClass
  Geometry: 1920x1080+0+0

1920x1080 which comes from what is shown in EXIFTOOL as:

- DisplayWindow : 0 0 1919 1079

So I believe there might be a bug that the Imagemagick developers will need to look into.

[dlemstra]

You can control the background color with -background:

convert -background black input.exr output.jpg

[tokejepsen]

Thanks @dlemstra! That'll work as a workaround atm.

To be specific we need to specify the background and alpha:

magick convert -background black -alpha copy input.exr output.png

It does remove the built-in cropping when converting between exrs, so not sure whether Image Magick want to look into this:

magick convert -background black -alpha copy input.exr output.exr

Personally I can live with the workaround solution.

[dlemstra]

What is the result that you are expecting? Do you want the cropped image instead?

[tokejepsen]

What is the result that you are expecting? Do you want the cropped image instead?

I would expect the exrs to match when converting between different compressions.
So if we compress the cropped.exr with:

magick convert -background black -alpha copy cropped.exr -compress DWAA result.exr

C:\Users\admin>"C:\Users\admin\Desktop\exiftool-11.71\exiftool(-k).exe" -s -ee -g1 -u -n -D C:\Users\admin\Desktop\cropped.exr
---- ExifTool ----
    - ExifToolVersion                 : 11.71
---- System ----
    - FileName                        : cropped.exr
    - Directory                       : C:/Users/admin/Desktop
    - FileSize                        : 37117
    - FileModifyDate                  : 2019:10:22 07:37:23+01:00
    - FileAccessDate                  : 2019:10:22 07:37:23+01:00
    - FileCreateDate                  : 2019:10:21 20:56:23+01:00
    - FilePermissions                 : 666
---- File ----
    - FileType                        : EXR
    - FileTypeExtension               : EXR
    - MIMEType                        : image/x-exr
    - ImageWidth                      : 522
    - ImageHeight                     : 394
---- OpenEXR ----
    - EXRVersion                      : 2
    - Layout                          : 0
    - Channels                        : A half 1 1, B half 1 1, G half 1 1, R half 1 1
    - Compression                     : 2
    - DataWindow                      : 660 190 1181 583
    - DisplayWindow                   : 0 0 1919 1079
    - LineOrder                       : 0
    - Nukefull_layer_names            : 0
    - Nukenode_hash                   : c22743bb50eb6fb8
    - Nukeversion                     : 11.0v4
    - PixelAspectRatio                : 1
    - ScreenWindowCenter              : 0 0
    - ScreenWindowWidth               : 1
    - Type                            : scanlineimage
    - Version                         : 1
---- Composite ----
    - ImageSize                       : 522 394
    - Megapixels                      : 0.205668

C:\Users\admin>"C:\Users\admin\Desktop\exiftool-11.71\exiftool(-k).exe" -s -ee -g1 -u -n -D C:\Users\admin\Desktop\result.exr
---- ExifTool ----
    - ExifToolVersion                 : 11.71
---- System ----
    - FileName                        : result.exr
    - Directory                       : C:/Users/admin/Desktop
    - FileSize                        : 45378
    - FileModifyDate                  : 2019:10:22 07:42:41+01:00
    - FileAccessDate                  : 2019:10:22 07:42:41+01:00
    - FileCreateDate                  : 2019:10:22 07:34:57+01:00
    - FilePermissions                 : 666
---- File ----
    - FileType                        : EXR
    - FileTypeExtension               : EXR
    - MIMEType                        : image/x-exr
    - ImageWidth                      : 1920
    - ImageHeight                     : 1080
---- OpenEXR ----
    - EXRVersion                      : 2
    - Layout                          : 0
    - Channels                        : A half 1 1, B half 1 1, G half 1 1, R half 1 1
    - Compression                     : 8
    - DataWindow                      : 0 0 1919 1079
    - DisplayWindow                   : 0 0 1919 1079
    - LineOrder                       : 0
    - PixelAspectRatio                : 1
    - ScreenWindowCenter              : 0 0
    - ScreenWindowWidth               : 1
---- Composite ----
    - ImageSize                       : 1920 1080
    - Megapixels                      : 2.0736

We end up with a result.exr that has the wrong DataWindow, 660 190 1181 583 compared to 0 0 1919 1079.

[dlemstra]

It took me a while but I finally understand that you would like to preserve the DataWindow. ImageMagick currently does not preserve this. Would it help you if it would be possible to only read the DataWindow and get an image that is only the cropped area?

[tokejepsen]

Would it help you if it would be possible to only read the DataWindow and get an image that is only the cropped area?

I would expect to preserve the DataWindow.

BUT with the solution of flooding the background with black transparent pixels works for me, so consider this issue non-priority and just something to flag for the future if someone else are having the same issue.

[tokejepsen]

For anyone following this or finding it later, you dont need -alpha copy since the cropped pixels are empty. The correct command is:

magick convert -background "rgba(0, 0, 0, 0)" cropped.exr result.exr

[fmw42]

In Imagemagick 7, use magick, not magick convert. The latter will give Imagemagick 6 behavior.

[lola-post]

We would like to +1 this behaviour as incorrect.

EXR's have a datawindow (autocrop) that needs to be preserved.
We would not expect a cropped image, but rather an image with the original resolution, with a datawindow inside it that could be bigger or smaller than the resolution of the image.

In vfx we use this for various reasons, examples:

• overscan
• autocropped cgo render (where an object may only fill a few pixels so the exr can be very small with the same resolution) In our applications, this function is called autocrop.