Add `SkipPixelData` option to `Parser`

[tcheever]

• For heavy imaging modalities, it is expensive to load the pixel data into memory, and for many use cases, unnecessary. This new option allows users to parse the other attributes without the resource hit.

Testing

$ go test -v -run TestNewParser ./...
=== RUN   TestNewParserSkipMetadataReadOnNewParserInit
--- PASS: TestNewParserSkipMetadataReadOnNewParserInit (0.00s)
=== RUN   TestNewParserSkipPixelData
--- PASS: TestNewParserSkipPixelData (0.01s)
=== RUN   TestNewParserPixelData
--- PASS: TestNewParserPixelData (0.62s)
PASS
ok      github.com/suyashkumar/dicom    0.677s
?       github.com/suyashkumar/dicom/cmd/dicomutil      [no test files]
?       github.com/suyashkumar/dicom/mocks/pkg/dicomio  [no test files]
?       github.com/suyashkumar/dicom/pkg/charset        [no test files]
testing: warning: no tests to run
PASS
ok      github.com/suyashkumar/dicom/pkg/dcmtime        0.011s [no tests to run]
?       github.com/suyashkumar/dicom/pkg/debug  [no test files]
?       github.com/suyashkumar/dicom/pkg/dicomio        [no test files]
testing: warning: no tests to run
PASS
ok      github.com/suyashkumar/dicom/pkg/frame  0.003s [no tests to run]
testing: warning: no tests to run
PASS
ok      github.com/suyashkumar/dicom/pkg/personname     0.017s [no tests to run]
testing: warning: no tests to run
PASS
ok      github.com/suyashkumar/dicom/pkg/tag    0.007s [no tests to run]
?       github.com/suyashkumar/dicom/pkg/uid    [no test files]
?       github.com/suyashkumar/dicom/pkg/vrraw  [no test files]

[tcheever]

Formal commit message aside, thank you for creating this library 😃. It has been very useful!

[suyashkumar]

Hi @tcheever just wanted to check in and see if you had a chance to consider the review comments? Thanks for the contribution! There may be some interplay with #245 as well as a heads up based on how these PRs progress.

[tcheever]

Hi @suyashkumar, thanks for the bump and the review. I did not see your comments and suggestions. I will get back to you as soon as possible.

[suyashkumar]

Hi @tcheever thanks for the responses, added a couple more comments for your consideration!

[tcheever]

@suyashkumar, if I'm understanding correctly, you do not want the option in the reader at all and you do not want the arg added to NewReader?

[NMerzVerily]

Having an option like this would also be useful for us.

[rronan]

We are also interested in that option, I'd be happy to help if needed.

[suyashkumar]

Thanks folks for the interest! I've circled back to this in #255, including making structural changes I wanted in #254 to support better option availability to read* methods in read.go (which was the subject of my comments in the review discussion here above).

Thanks @tcheever and others for the discussion and interest in this useful feature!

[suyashkumar]

Going to close this for now, since this feature was introduced in #255 with the new options availability (merged to main)! @NMerzVerily @rronan @b3n3d17 @tcheever please feel free to kick the tires on it and let us know how it goes.