I think this was common with VHS.psycopathicteen wrote:I find it pretty funny how a lot of Europeans online say that skin colors on NTSC appear as either green or purple, yet, I never seen it happen on any of the TVs I had.
- ... multipath reception in antennas and signal reflections in impedance-unmatched electrical connections will cause differential (brightness-dependent) phase shift. Differential phase errors cannot be removed by the viewer using the Hue control, as that one will only correct linear phase errors. The beloved NES being a serious offender. The PAL patent on the other hand explicitly mentions its ability to even remove differential phase errors, as my comparison of the PAL NES' output with Simple PAL versus Full PAL demonstrates.
- ... the very presence of a Hue knob not only in monitors but also in video production equipment meaning one more setting than can and will be improperly adjusted.
- ... a black level of 7.5 percent that was almost impossible to get right without an oscilloscope in the pre-digital days. Basically everyone else, including all PAL countries, use a black level of zero.
- ... RGB primaries that were obsolete almost immediately after the standard was adopted yet never formally changed, leading to confusion among everyone about what the correct colorimetry is, and strange correction matrices in production and consumer equipment. For PAL, the European Broadcasting Union simply said in 1970: here are new primaries based on current technology, and here are permissible deviations: use them and shut up. Worked so well that they were used with minimal changes in HDTV (as Rec. 709).
- ... generally much more lax broadcast and somewhat more lax equipment production standards in NTSC regions (although that's not the fault of the system itself)
Then again, if I look at some YouTube videos...
I wonder how many people would notice if the colorimetry was different without the correction matrices. If you can get a wider color gamut, you might as well show it off.... RGB primaries that were obsolete almost immediately after the standard was adopted yet never formally changed, leading to confusion among everyone about what the correct colorimetry is, and strange correction matrices in production and consumer equipment.
Is the first one have a ".6mhz" filter on both the encoder and decoder side? Also, the last one DOES look familiar, like it's how my old tv looked like.NewRisingSun wrote:RF video, overall 4.2 MHz bandwidth, equiband YUV decoding at 0.6 MHz.RF video, overall 4.2 MHz bandwidth, equiband YUV decoding at 1.5 MHz. RF video, overall 4.2 MHz bandwidth, 1953 NTSC YIQ decoding with I at 1.5 MHz and Q at 0.6 MHz. This one looks really weird in the yellow-green bushes, because the unequal bandwidths result in funky transitory colors that don't appear with equal bandwidths, even when they're low. Baseband composite video, unrestricted overall bandwidth, equiband YUV decoding at 1.5 MHz: Baseband composite video, unrestricted overall bandwidth, equiband YUV decoding at 3.5 MHz: The last one is never used, because as you can see, the high chroma bandwidth basically steals all the luma detail, and so is pointless.
- "Linear light signals" are the signals you get when you remove gamma-pre-correction, i.e. LinearR = R^2.2, 0.0 <= R <= 1.0.
- "Gamma pre-corrected signals" are the normal RGB values you use. As the article referenced in the file explains, proper conversion requires linear light signals. When you use normal gamma pre-corrected signals, you must specify two chromaticity points for which the inevitably resulting errors will be minimized.
- The "Parker (original)" and "Parker (modified)" sheets differ in how white point differences are treated.
- The "Common settings" sheet contains a number of color spaces that the literature lists as being "common" for television sets of a particular era, as well as the color spaces defined by the various standards documents. "sRGB" uses "CCIR Rec. 709" primaries and white point D65.
- The "Gain/Angle" are the result of folding the NTSC YUV-to-RGB* and "Correction for gamma pre-corrected signals" matrices into one matrix and are the values you would enter for example into Nestopia's NTSC palette generator under "Advanced" (Nestopia for some reason requires Gain to be entered divided by two).
- (11.7 KiB) Downloaded 153 times
Code: Select all
Correction for gamma pre-corrected signals R's G's B's V U Gain Angle R't= 1.2903 -0.2705 -0.0198 R'-Y'= 1.628 0.066 1.629 87.7 ° G't= -0.0037 0.9516 0.0521 G'-Y'= -0.557 -0.269 0.618 244.2 ° B't= 0.0317 -0.1982 1.1665 B'-Y'= 0.151 2.445 2.450 3.5 °
Code: Select all
// Convert from 1953 NTSC (with D65 white point) to sRGB color space float R = (r>=0.0812)? pow((r+0.099)/1.099, 1.0/0.45): r/4.500; float G = (g>=0.0812)? pow((g+0.099)/1.099, 1.0/0.45): g/4.500; float B = (b>=0.0812)? pow((b+0.099)/1.099, 1.0/0.45): b/4.500; float newR = 1.4607*R -0.3845*G -0.0761*B; float newG =-0.0266*R +0.9654*G +0.0612*G; float newB =-0.0264*R -0.0414*G +1.0678*B; if (newR<0.0) newR=0.0; if (newR>1.0) newR=1.0; if (newG<0.0) newG=0.0; if (newG>1.0) newG=1.0; if (newB<0.0) newB=0.0; if (newB>1.0) newB=1.0; r = (newR>=0.018)? 1.099*pow(newR, 0.45)-0.099: 4.5*newR; g = (newG>=0.018)? 1.099*pow(newG, 0.45)-0.099: 4.5*newG; b = (newB>=0.018)? 1.099*pow(newB, 0.45)-0.099: 4.5*newB;
This CAN'T be a coincidence that such a simple digital filter would hit the 1.3 Mhz bandwidth so closely.