[SPARK-23205][ML] Update ImageSchema.readImages to correctly set alpha values for four-channel images #20389
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srowen
approved these changes
Jan 24, 2018
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Test build #86607 has finished for PR 20389 at commit
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Test build #86609 has finished for PR 20389 at commit
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Thanks for the reviews @srowen, @dongjoon-hyun! Would it make sense to merge this before Spark 2.3 is released & if so would one of you be able to do so? |
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It's minor, though that cuts two ways - low risk to merge, but not critical. I think that's a moderately important issue for this module and a clean fix so I'd put it in branch 2.3 |
viirya
reviewed
Jan 25, 2018
| @@ -169,8 +169,7 @@ object ImageSchema { | |||
| var offset = 0 | |||
| for (h <- 0 until height) { | |||
| for (w <- 0 until width) { | |||
| val color = new Color(img.getRGB(w, h)) | |||
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| val color = new Color(img.getRGB(w, h), nChannels == 4) | |||
There was a problem hiding this comment.
Why don't directly use hasAlpha?
viirya
reviewed
Jan 25, 2018
| @@ -169,8 +169,7 @@ object ImageSchema { | |||
| var offset = 0 | |||
| for (h <- 0 until height) { | |||
| for (w <- 0 until width) { | |||
| val color = new Color(img.getRGB(w, h)) | |||
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| val color = new Color(img.getRGB(w, h), nChannels == 4) | |||
| decoded(offset) = color.getBlue.toByte | |||
| decoded(offset + 1) = color.getGreen.toByte | |||
| decoded(offset + 2) = color.getRed.toByte | |||
There was a problem hiding this comment.
At line 177,
if (nChannels == 4) {
decoded(offset + 3) = color.getAlpha.toByte
}We can directly use hasAlpha too, instead of indirectly comparing nChannels.
srowen
approved these changes
Jan 25, 2018
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Test build #86645 has finished for PR 20389 at commit
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asfgit
pushed a commit
that referenced
this pull request
Jan 26, 2018
…a values for four-channel images ## What changes were proposed in this pull request? When parsing raw image data in ImageSchema.decode(), we use a [java.awt.Color](https://docs.oracle.com/javase/7/docs/api/java/awt/Color.html#Color(int)) constructor that sets alpha = 255, even for four-channel images (which may have different alpha values). This PR fixes this issue & adds a unit test to verify correctness of reading four-channel images. ## How was this patch tested? Updates an existing unit test ("readImages pixel values test" in `ImageSchemaSuite`) to also verify correctness when reading a four-channel image. Author: Sid Murching <sid.murching@databricks.com> Closes #20389 from smurching/image-schema-bugfix. (cherry picked from commit 7bd46d9) Signed-off-by: Sean Owen <sowen@cloudera.com>
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Merged to master/2.3 |
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What changes were proposed in this pull request?
When parsing raw image data in ImageSchema.decode(), we use a java.awt.Color constructor that sets alpha = 255, even for four-channel images (which may have different alpha values). This PR fixes this issue & adds a unit test to verify correctness of reading four-channel images.
How was this patch tested?
Updates an existing unit test ("readImages pixel values test" in
ImageSchemaSuite) to also verify correctness when reading a four-channel image.