Latest Contributions by PeterBecker

I tool a look. This is a strange file. It appears to be drone imagery that was originally 8bit and has been exported as a 12bit JPEG compressed image with 256 being defined as NoData and set using JPEG12bit compression . It is not clear to me if this the original image rotated or export from an orthorectification process. Such processing creates artifacts at the edges. (In the following I set NoData to organize to highlight the issue) JPEG has an issue in that traditionally it does not have NoData. The software that produced the image (could have been ArcMap) set NoData as 256. Please check this and set to 255 instead which would keep it in the 8bit range and compress much better. You will still see the JPEG artifacts. There are different ways to handle the masking of 8bit JPEG but it depends on how the image was exported. The 12bit version of JPEG is not natively supported in ArcGIS Pro hence it is converting to 16bit and using Deflate (lossless) compression hence the increase in size. There is a relatively complex work around using GLAD that can be done, but I recommend checking first on the source of how the images were created. ... View more

Yes, It appears from afar to be correct   ... View more

There is very little point compressing imagery using ZIP. I recommend against using ZIP to compress a directory of images. If you are looking for lossless compression of imagery then simplest is to use Deflate or LZW. There are some better lossless compression methods, but the differences will be limited. If you have collection of imagery that are not compressed and you want to compress them then its better run them through Optimize Raster to compress. Some datasets such as elevation compress better using compression such as LERC. For more details on how to convert and optimize imagery check out OptimizeRasters.    Using Mosaic Dataset is the best way to manage the data as this references the source data (full resolution and any pyramids) and enables the definition of additional attributes, functions to process the data on the fly and enables quick access to all the data either directly in ArcGIS Pro or serving as image services through ArcGIS Image Server.  When directly using the mosaic dataset in ArcGIS Pro it acts as a layer defining functions applied to the appropriate imagery. Yes you are accessing the full resolution source data when zooming in. The compression for transmission that you set is the compression used to transmit the data. It is the client application that can set it and the compression quality at any time. There is no reason to only allow ‘None’.  As you mention setting this to say JPEG  can speed up transmission of the data. There are Export and download options. Export will typically resample the data and apply any defined functions on the data. The application defines the resampling compression etc. Download downloads the original pixels were possible. I say were possible as if you use say a MrSID then the data is compressed and the data must first be decompressed before writing it to a new file so the data structure will change but not the pixel values (unless you define another lossy compression). You can directly use Mosaic datasets as input to your analysis tools. This enables large collections of imagery and rasters to be seen as a single dataset, with control of many properties. If you want to ensure that the pixels are exactly the same as those stored on disk then you should use the environment variables to set the appropriate pixel size, projection and extent to ensure the requested pixels align with the source. Do check out the ArcGIS Imagery Workflows page, it provides lots of best practices ... View more