If the quantization tables follow the standard trend of limited compression in the low-frequency components rising to moderate compression in the high-frequency components, then the approximate quality factor may indeed give one an idea as to how the overall quality may appear. Therefore, as an incredibly rough approximation, a calculation has been made for each source to derive the closest / approximate IJG quality factor for a given table. ![]() So, what about other digicams / software editors that didn't use the IJG scaling method? People always love to make comparisons, and comparing multiple 64-element matrices is not intuitive to the average person. If we know that a given program has used the IJG scaling method, then we can indeed make a comparison, because all numbers in the matrices will move according to the algorithm in a similar manner. That said, many software programs and some digicams are indeed using scaled versions of this standard table. A quality factor of 100 does not mean Lossless compression! Instead, it generally represents the quality factor that will generate the highest quality compressed image with the provided scaling algorithm. This is NOT a percentage! It is merely a number from 1-100 representing the scaling factor used in generating the table. Convert files to a specific format nconvert -out tiff file1.pic file2.jpg file3. Type 'nconvert -help > nchelp.txt' to save the help text into the file 'nchelp.txt'. Type 'nconvert -help' for available options. The IJG group has proposed a method of scaling these coefficients according to a “quality factor” scale. NConvert is the multi-format commandline image converter for Win32, Linux, DOS, OS/2, and other platforms. So, then why are “quality” numbers listed for each camera/software source? Many programs encode their JPEG images using quantization tables that are generated by scaling the coefficients in a “standard“ table that is provided in the ITU-T specification. Trying to make a comparison between a pair of matrices is not at all straightforward (or always possible). JPEG compression quality is actually defined by a pair of quantization tables (each with an array of 64 values). Re: XnConvert for Dummies Post by Leslie » Sun 12:04 pm So basically I am (trying to ) batch process from raw size to 12 x 8 and then add the watermark which is also 12 x 8. If I set checkbox remember or save my choice - this not matter with next start. My hardware : CPU Intel i7-6800K 3.4 stock without Turbo Boost, RAM 32 GB 2400 15-15-15-35-CR2 1800 12-12-12-28-CR1 Quad channel.Calvin Hass (Comparing JPEG Quality » Important note about Quality Factors) wrote:It is extremely important that the reader understand that compression quality cannot truly be represented by a single value. XnConvert does not remember settings by Xn User Sat 1:40 pm Hi ) XnConvert starting with version 1.76 and newer does NOT remember my choice in process convert. Here video without openjp2.dll and using only lwf_jp2.dll from XnView 2.47 ![]() Please study what not that with openjp2.dll and if need rewrite this module. ![]() SMT chekbox in this cases value not have. If I delete this openjp2.dll and use only lwf_jp2.dll - All works very fast.Īs only I recovering openjp2.dll - all works force slower. Here video as XnConvert work with original plugins convert from JPEG2000 to BMP, and convert from BMP to JPEG2000 if used SMT Īfter pa hours waiting and learning this problem : ![]() If you be convert with SMT - will be long delay before start convertion from JPEG2000 to any other format. And compare time this operation if convert with SMT and if convert without SMT. Here images for test, please download and do convertion from PNG to JPEG2000 and, next do convertion from JPEG2000 to PNG and other format. Yes, without SMT - this bug not reproducing.
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