private void PreProcess(IImageReader <T2> reader, ImageFormat imageFormat, uint amount, uint?desiredSize)
{
if (reader == null)
{
throw new ArgumentNullException(nameof(reader));
}
if (amount > 1)
{
// calculate hashes of images for the defined amount for each axis
IList <PositionAxisContainerModel <string> > hashes = new List <PositionAxisContainerModel <string> >();
IDictionary <AxisType, uint[]> newMap = new Dictionary <AxisType, uint[]>();
IAxisPositionMapper mapper = reader.Mapper;
if (mapper == null)
{
throw new UnexpectedNullException("The image reader does not contain a mapper.");
}
foreach (AxisType axisType in (AxisType[])Enum.GetValues(typeof(AxisType)))
{
newMap[axisType] = new uint[amount];
for (uint i = 0; i < amount; i++)
{
// set initial mapped positions
newMap[axisType][i] = mapper.GetMappedPosition(axisType, i);
using (var bitmap = reader.ExtractPosition(axisType, i, desiredSize))
{
if (bitmap != null)
{
string hash = Cryptography.CalculateSHA1Hash(bitmap.ToByteArray(imageFormat));
hashes.Add(new PositionAxisContainerModel <string>(i, axisType, hash));
}
}
}
}
// calculate new mapped positions based on the hashes
foreach (AxisType axisType in (AxisType[])Enum.GetValues(typeof(AxisType)))
{
var axisHashes = hashes.Where(e => e.AxisType == axisType);
// find the most likely hash representing an empty image
string emptyHash = axisHashes.GroupBy(e => e.Entity)
.Where(e => e.Count() > 1).OrderBy(e => e.Count()).Select(e => e.Key).FirstOrDefault();
if (emptyHash != null)
{
var nonEmptyHashes = axisHashes.Where(e => e.Entity != emptyHash).OrderBy(e => e.Position);
var startPosition = nonEmptyHashes.FirstOrDefault();
var endPosition = nonEmptyHashes.LastOrDefault();
if (startPosition != null && endPosition != null)
{
if (startPosition == endPosition)
{
// set the same mappedPosition for all positions
for (int i = 0; i < amount; i++)
{
newMap[axisType][i] = mapper.GetMappedPosition(axisType, startPosition.Position);
}
}
else
{
// calculate mappedPosition between startPosition and endPosition
uint mappedStartPosition = mapper.GetMappedPosition(axisType, startPosition.Position);
uint mappedEndPosition = mapper.GetMappedPosition(axisType, endPosition.Position);
uint length = mappedEndPosition - mappedStartPosition;
for (uint i = 0; i < amount; i++)
{
newMap[axisType][i] = mappedStartPosition + mapper.CalculateMappedPosition(amount, length, i);
}
}
}
}
}
// TODO: distribute equally (newMap) to avoid re-use of the same image excessively compared to others
/*
* Request:
* - Extract x images and each image at least once.
* Special case:
* - Less than x images can be extracted.
* Preferred behaviour:
* - Prioritize images in the middle for re-use.
*/
// set a new mapper with the new map
reader.Mapper = new AxisPositionMapper(newMap);
}
}
