# Revision history [back]

Not really, because you always have to convert the Image into a grayscale Image for the SIFT algorithm. But beside that, a format which has a small lossless conversion from the raw camera data would be good (e.g. JPEG is no lossless conversion of the original raw data).

Not really, because you always have to convert the Image into a grayscale Image for the SIFT algorithm. But beside that, a format which has a small lossless conversion from the raw camera data would be good (e.g. JPEG is no lossless conversion of the original raw data).data).

On the other hand, if you use a JPEG as reference Image and just try the recognition also in JPEG, the conversion of JPEG is nonrelevant.

Not really, because you always have to convert the Image into a grayscale Image for the SIFT algorithm. But beside that, a format which has a small lossless conversion from the raw camera data would be good (e.g. JPEG is no lossless conversion of the original raw data).

On the other hand, if you use a JPEG as reference Image and just try the recognition also in JPEG, the conversion of JPEG is nonrelevant.

For some calrification opencv's SIFT checks for a CV_8U Type Image and throws an error if the Image is not that type:

void SIFT_Impl::detectAndCompute(InputArray _image, InputArray _mask,
std::vector<KeyPoint>& keypoints,
OutputArray _descriptors,
bool useProvidedKeypoints)
{
int firstOctave = -1, actualNOctaves = 0, actualNLayers = 0;

if( image.empty() || image.depth() != CV_8U )
CV_Error( Error::StsBadArg, "image is empty or has incorrect depth (!=CV_8U)" );


Not really, because you always have to convert the Image into a grayscale Image for the SIFT algorithm. But beside that, a format which has a small lossless conversion from the raw camera data would be good (e.g. JPEG is no lossless conversion of the original raw data).

On the other hand, if you use a JPEG as reference Image and just try the recognition also in JPEG, the conversion of JPEG is nonrelevant.

For some calrification opencv's SIFT checks for a CV_8U Type Image and throws an error if the Image is not that type:

void SIFT_Impl::detectAndCompute(InputArray _image, InputArray _mask,
std::vector<KeyPoint>& keypoints,
OutputArray _descriptors,
bool useProvidedKeypoints)
{
int firstOctave = -1, actualNOctaves = 0, actualNLayers = 0;