| One line summary | Validating JPEG2000 files after conversion from TIFF and tracing source of errors |
| Detailed description | There are number of potential tools and algorithms that can be used to verify quality of JPEG2000 files. It may be necessary to use a range of tools to validate all aspects of the JPEG2000 that are considered significant. XML schemas for JPEG2000 profiles would be useful for validating characterisation outputs. One possible workflow might be: 1. Use a JHOVE2 module that wraps a decoder such as OpenJPEG so that a JHOVE XML file can be generated providing a characterisation of both the format and the bit stream. 2. Validate XML output from JHOVE against a relevent profile schema 3. Analyse and record the PSNR value of the files and compare against the acceptable quality thresholds 4. Analyse and record against ??? and compare values against acceptable quality thresholds 5. For appropriate material types, carry out an OCR compare test between original and converted files 6. Ideally combine results from tests into a human-readable report for each batch of images (e.g. on a daily basis) Assumptions: 1. Someone will create a JHOVE2 JPEG2000 characerisation wrapper including the OpenJPEG decode step 2. An XML schema will be created for JPEG2000 profiles 3. Application/applications can be written to carry out the necessary comparisons and produce the report(s) 4. That these comprise the main quality assurance issues - although other tests could be introduced for other significant properties 5. That this process will not create a significant overhead in terms of processing time, but will work within the confines of the workflow timescale (20,000 images per month for archives, for example). |
| Solution champion | Christy Henshaw |
| Git link | |
| Evaluation | This appears to be a workable solution, but requires further thought around exact tools/mechanisms to be used, and which characteristics are considered significant. It would need to be tested, both for ability to validate, and for performance. Support will be required on some level, to wrap these tools into a useful package. It is likely that this tool could be incoporated into our workflow using our workflow system using a programming interface. If this validation "package" were to be created and implemented, it would greatly improve assurance of files both in-house, and for images supplied from external vendors/partners. |
| Tool (link) | OpenJPEG |
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