| public jpeg_set_colorspace ( J_COLOR_SPACE colorspace ) : void | ||
| colorspace | J_COLOR_SPACE | The required colorspace. |
| return | void | |
public void jpeg_set_colorspace(J_COLOR_SPACE colorspace)
{
int ci;
/* Safety check to ensure start_compress not called yet. */
if (m_global_state != JpegState.CSTATE_START)
ERREXIT(J_MESSAGE_CODE.JERR_BAD_STATE, (int)m_global_state);
/* For all colorspaces, we use Q and Huff tables 0 for luminance components,
* tables 1 for chrominance components.
*/
m_jpeg_color_space = colorspace;
m_write_JFIF_header = false; /* No marker for non-JFIF colorspaces */
m_write_Adobe_marker = false; /* write no Adobe marker by default */
switch (colorspace)
{
case J_COLOR_SPACE.JCS_UNKNOWN:
m_num_components = m_input_components;
if (m_num_components < 1 || m_num_components > JpegConstants.MAX_COMPONENTS)
ERREXIT(J_MESSAGE_CODE.JERR_COMPONENT_COUNT, m_num_components, JpegConstants.MAX_COMPONENTS);
for (ci = 0; ci < m_num_components; ci++)
jpeg_set_colorspace_SET_COMP(ci, ci, 1, 1, 0, 0, 0);
break;
case J_COLOR_SPACE.JCS_GRAYSCALE:
m_write_JFIF_header = true; /* Write a JFIF marker */
m_num_components = 1;
/* JFIF specifies component ID 1 */
jpeg_set_colorspace_SET_COMP(0, 0x01, 1, 1, 0, 0, 0);
break;
case J_COLOR_SPACE.JCS_RGB:
m_write_Adobe_marker = true; /* write Adobe marker to flag RGB */
m_num_components = 3;
jpeg_set_colorspace_SET_COMP(0, 0x52 /* 'R' */, 1, 1, 0,
color_transform == J_COLOR_TRANSFORM.JCT_SUBTRACT_GREEN ? 1 : 0,
color_transform == J_COLOR_TRANSFORM.JCT_SUBTRACT_GREEN ? 1 : 0);
jpeg_set_colorspace_SET_COMP(1, 0x47 /* 'G' */, 1, 1, 0, 0, 0);
jpeg_set_colorspace_SET_COMP(2, 0x42 /* 'B' */, 1, 1, 0,
color_transform == J_COLOR_TRANSFORM.JCT_SUBTRACT_GREEN ? 1 : 0,
color_transform == J_COLOR_TRANSFORM.JCT_SUBTRACT_GREEN ? 1 : 0);
break;
case J_COLOR_SPACE.JCS_YCbCr:
m_write_JFIF_header = true; /* Write a JFIF marker */
m_num_components = 3;
/* JFIF specifies component IDs 1,2,3 */
/* We default to 2x2 subsamples of chrominance */
jpeg_set_colorspace_SET_COMP(0, 0x01, 2, 2, 0, 0, 0);
jpeg_set_colorspace_SET_COMP(1, 0x02, 1, 1, 1, 1, 1);
jpeg_set_colorspace_SET_COMP(2, 0x03, 1, 1, 1, 1, 1);
break;
case J_COLOR_SPACE.JCS_CMYK:
m_write_Adobe_marker = true; /* write Adobe marker to flag CMYK */
m_num_components = 4;
jpeg_set_colorspace_SET_COMP(0, 0x43 /* 'C' */, 1, 1, 0, 0, 0);
jpeg_set_colorspace_SET_COMP(1, 0x4D /* 'M' */, 1, 1, 0, 0, 0);
jpeg_set_colorspace_SET_COMP(2, 0x59 /* 'Y' */, 1, 1, 0, 0, 0);
jpeg_set_colorspace_SET_COMP(3, 0x4B /* 'K' */, 1, 1, 0, 0, 0);
break;
case J_COLOR_SPACE.JCS_YCCK:
m_write_Adobe_marker = true; /* write Adobe marker to flag YCCK */
m_num_components = 4;
jpeg_set_colorspace_SET_COMP(0, 0x01, 2, 2, 0, 0, 0);
jpeg_set_colorspace_SET_COMP(1, 0x02, 1, 1, 1, 1, 1);
jpeg_set_colorspace_SET_COMP(2, 0x03, 1, 1, 1, 1, 1);
jpeg_set_colorspace_SET_COMP(3, 0x04, 2, 2, 0, 0, 0);
break;
case J_COLOR_SPACE.JCS_BG_RGB:
m_write_JFIF_header = true; /* Write a JFIF marker */
JFIF_major_version = 2; /* Set JFIF major version = 2 */
m_num_components = 3;
/* Add offset 0x20 to the normal R/G/B component IDs */
jpeg_set_colorspace_SET_COMP(0, 0x72 /* 'r' */, 1, 1, 0,
color_transform == J_COLOR_TRANSFORM.JCT_SUBTRACT_GREEN ? 1 : 0,
color_transform == J_COLOR_TRANSFORM.JCT_SUBTRACT_GREEN ? 1 : 0);
jpeg_set_colorspace_SET_COMP(1, 0x67 /* 'g' */, 1, 1, 0, 0, 0);
jpeg_set_colorspace_SET_COMP(2, 0x62 /* 'b' */, 1, 1, 0,
color_transform == J_COLOR_TRANSFORM.JCT_SUBTRACT_GREEN ? 1 : 0,
color_transform == J_COLOR_TRANSFORM.JCT_SUBTRACT_GREEN ? 1 : 0);
break;
case J_COLOR_SPACE.JCS_BG_YCC:
m_write_JFIF_header = true; /* Write a JFIF marker */
JFIF_major_version = 2; /* Set JFIF major version = 2 */
m_num_components = 3;
/* Add offset 0x20 to the normal Cb/Cr component IDs */
/* We default to 2x2 subsamples of chrominance */
jpeg_set_colorspace_SET_COMP(0, 0x01, 2, 2, 0, 0, 0);
jpeg_set_colorspace_SET_COMP(1, 0x22, 1, 1, 1, 1, 1);
jpeg_set_colorspace_SET_COMP(2, 0x23, 1, 1, 1, 1, 1);
break;
default:
ERREXIT(J_MESSAGE_CODE.JERR_BAD_J_COLORSPACE);
break;
}
}
/// <summary>
/// Initializes the compression object with default parameters, then copy from the source object
/// all parameters needed for lossless transcoding.
/// </summary>
/// <param name="dstinfo">Target JPEG compression object.</param>
/// <remarks>Parameters that can be varied without loss (such as scan script and
/// Huffman optimization) are left in their default states.</remarks>
public void jpeg_copy_critical_parameters(jpeg_compress_struct dstinfo)
{
/* Safety check to ensure start_compress not called yet. */
if (dstinfo.m_global_state != JpegState.CSTATE_START)
ERREXIT(J_MESSAGE_CODE.JERR_BAD_STATE, (int)dstinfo.m_global_state);
/* Copy fundamental image dimensions */
dstinfo.m_image_width = m_image_width;
dstinfo.m_image_height = m_image_height;
dstinfo.m_input_components = m_num_components;
dstinfo.m_in_color_space = m_jpeg_color_space;
/* Initialize all parameters to default values */
dstinfo.jpeg_set_defaults();
/* jpeg_set_defaults may choose wrong colorspace, eg YCbCr if input is RGB.
* Fix it to get the right header markers for the image colorspace.
*/
dstinfo.jpeg_set_colorspace(m_jpeg_color_space);
dstinfo.m_data_precision = m_data_precision;
dstinfo.m_CCIR601_sampling = m_CCIR601_sampling;
/* Copy the source's quantization tables. */
for (int tblno = 0; tblno < JpegConstants.NUM_QUANT_TBLS; tblno++)
{
if (m_quant_tbl_ptrs[tblno] != null)
{
if (dstinfo.m_quant_tbl_ptrs[tblno] == null)
dstinfo.m_quant_tbl_ptrs[tblno] = new JQUANT_TBL();
Buffer.BlockCopy(m_quant_tbl_ptrs[tblno].quantval, 0,
dstinfo.m_quant_tbl_ptrs[tblno].quantval, 0,
dstinfo.m_quant_tbl_ptrs[tblno].quantval.Length * sizeof(short));
dstinfo.m_quant_tbl_ptrs[tblno].Sent_table = false;
}
}
/* Copy the source's per-component info.
* Note we assume jpeg_set_defaults has allocated the dest comp_info array.
*/
dstinfo.m_num_components = m_num_components;
if (dstinfo.m_num_components < 1 || dstinfo.m_num_components> JpegConstants.MAX_COMPONENTS)
ERREXIT(J_MESSAGE_CODE.JERR_COMPONENT_COUNT, dstinfo.m_num_components, JpegConstants.MAX_COMPONENTS);
for (int ci = 0; ci < dstinfo.m_num_components; ci++)
{
dstinfo.Component_info[ci].Component_id = m_comp_info[ci].Component_id;
dstinfo.Component_info[ci].H_samp_factor = m_comp_info[ci].H_samp_factor;
dstinfo.Component_info[ci].V_samp_factor = m_comp_info[ci].V_samp_factor;
dstinfo.Component_info[ci].Quant_tbl_no = m_comp_info[ci].Quant_tbl_no;
/* Make sure saved quantization table for component matches the qtable
* slot. If not, the input file re-used this qtable slot.
* IJG encoder currently cannot duplicate this.
*/
int tblno = dstinfo.Component_info[ci].Quant_tbl_no;
if (tblno < 0 || tblno >= JpegConstants.NUM_QUANT_TBLS || m_quant_tbl_ptrs[tblno] == null)
ERREXIT(J_MESSAGE_CODE.JERR_NO_QUANT_TABLE, tblno);
JQUANT_TBL c_quant = m_comp_info[ci].quant_table;
if (c_quant != null)
{
JQUANT_TBL slot_quant = m_quant_tbl_ptrs[tblno];
for (int coefi = 0; coefi < JpegConstants.DCTSIZE2; coefi++)
{
if (c_quant.quantval[coefi] != slot_quant.quantval[coefi])
ERREXIT(J_MESSAGE_CODE.JERR_MISMATCHED_QUANT_TABLE, tblno);
}
}
/* Note: we do not copy the source's Huffman table assignments;
* instead we rely on jpeg_set_colorspace to have made a suitable choice.
*/
}
/* Also copy JFIF version and resolution information, if available.
* Strictly speaking this isn't "critical" info, but it's nearly
* always appropriate to copy it if available. In particular,
* if the application chooses to copy JFIF 1.02 extension markers from
* the source file, we need to copy the version to make sure we don't
* emit a file that has 1.02 extensions but a claimed version of 1.01.
* We will *not*, however, copy version info from mislabeled "2.01" files.
*/
if (m_saw_JFIF_marker)
{
if (m_JFIF_major_version == 1)
{
dstinfo.m_JFIF_major_version = m_JFIF_major_version;
dstinfo.m_JFIF_minor_version = m_JFIF_minor_version;
}
dstinfo.m_density_unit = m_density_unit;
dstinfo.m_X_density = (short)m_X_density;
dstinfo.m_Y_density = (short)m_Y_density;
}
}
