On 07/03/13 15:48, ghostfox3 wrote: > Thanks all for the helpful responses. > > Carl - Yes .. Something is going wrong with the renaming of the > processed images. It seems is is not functioning properly. > > I searched for the preferences to change the image info to pixels that > you spoke of but cannot locate that. > > Ermanno - your comment that the heavy compression is a worry ... the > quality is worse than the original ... should this be happening when > crop for photo service is applied? Well.. JPEG is a lossy compression. That is, you lose quality, starting from the tiny details. If you modify a JPEG file and then you save it again, you recreate a JPEG file: you add lossy compression to lossy compression, losing more details and creating artifacts. You will note this in a image containing some text. Summing up, If you want high quality, you should start from a TIFF image (lossless compression or no compression at all), then do all the modification you need and only in the end you save it in JPEG format and *never* modify that image. This is what you (and anyone else modifying a photo) should do. But a light compression could be tolerated. Only you can judge. See the two photos side by side at high magnification and see if you note differences and if those differences affect the image's quality. > > Loretta Ciao, Ermanno > > --- In
gcmac@yahoogroups.com <mailto:gcmac%40yahoogroups.com>, Ermanno > Polli <erpol@...> wrote: > > > > On 07/03/13 09:21, Carl von Einem wrote: > > > From the screenshot I can see that you cropped the longer side of your > > > image. The new image uses the extension .tif in the file name but the > > > file format is actually a JPG. > > > So something went wrong with the renaming of your processed image. > > > > > > The term resolution has nothing to do with image size (in pixels), > let's > > > just have a closer look at the information in your screenshot: > > > > > > left image: 6.43 x 10.04 inch @ 300 ppi > > > right image: 26.78 x 40.17 inch @ 72 dpi > > > > > > Now let's compare the width of both images using a calculator: > > > left: 300 pixels x 6.43 = 1929 pixels > > > right: 72 pixels x 26.78 = 1928 pixels (rounded to full pixel count) > > > > I may add that the pixel number hasn't significantly changed, too: > > left image: 5.8 Mpix > > right image: 5.6 Mpix > > (This is a shortcut to your conclusions
) > > > > So the missing pixels could be due to the small crop at the bottom. > > > > Despite the .tif suffix, the right image *is* a JPEG, as you said > > before, you may see it from the file size that is heavily shrinked. > > > > Loretta, I would worry more about this thinning (1:20 compression). You > > may see the same number of pixel but the pixel contents is *not* the > > same. It's "rebuilt". The quality is worse than the original. It may or > > may not satisfy you.. > > > > > > Ciao, > > Ermanno > > > > > The "missing" pixel in the right image's width is just a rounding error > > > in GC's info box: 1929 pixels / 72 = 26,79166666667 > > > > > > Hey, I found a bug
> > > > > > I think somewhere in the prefs you can find an option to also display > > > the pixel size in that info area. > > > > > > PPI reads "pixels per inch" or pixel density, it's nicely explained in > > > this short article:
http://wiki.panotools.org/DPI > > > > > > Back to the naming problem I mentioned first: I also once shot a photo > > > "DSC_0307" which looks completely different?! > > > Therefore I recommend to rename images to something unique like > > > <your initials> + <yyyymmdd> + <hhmmss> + <original file number> > > > That's a simple one line command in Exiftool which renames thousands of > > > images in seconds. > > > > > > Carl > > > > > > ghostfox3 schrieb am 07.03.13 04:59: > > > > Alfred, > > > > > > > > Thanks for your reply. I do not know where my response went that I > > > referred to in my last post. > > > > > > > > I have a screen shot showing the image info before and after. The > > > size and a resolution changes, though I have selected 300 ppi and it is > > > not saving as a jpeg as I have also selected. > > > > > > > > > > > > Loretta > > > > > > > > > > > > > > > > --- In
gcmac@yahoogroups.com <mailto:gcmac%40yahoogroups.com> > <mailto:gcmac%40yahoogroups.com>, Alfred > > > J Treder<altreder@> wrote: > > > >> > > > >> Loretta, > > > >> > > > >> Probably nothing bad is happening. The conversion from TIFF to JPEG > > > is done without changing the number of pixels or the proportions of the > > > image. You said earlier that you were producing 4x6 images at 300 ppi, > > > which would be a good resolution for printing. That means you are > > > creating files that are 1200 pixels by 1800 pixels. After the > conversion > > > to JPEG, you still have a file that will print 4x6 inches at 300 > ppi, if > > > you direct the printing process to print the file in the 4x6 size. When > > > you see an indication that the resolution is 72 ppi, the associated > > > image size would be 16.667x25.000 inches. The same file can be printed > > > or displayed larger or smaller, depending on how the printing or > display > > > instructions are set up. Graphic Converter makes this easy, generally, > > > but does also allow a lot of options. > > > >> > > > >> I may have said too much or perhaps not understood your problem. Are > > > you saying that after conversion to JPEG the resolution is at 72 > ppi AND > > > the size is 4 inches by 6 inches? If that were true you would have a > > > problem to solve for sure. One test of that would be to look at the > file > > > on your computer monitor, and crank up its size to bigger than 4x6 > > > inches. It would be pixelated if the file had become reduced in pixel > > > density, and would look normal on the screen even blown up 2 or 3 times > > > if the file was still OK. > > > >> > > > >> Al Treder > > > >> > > > >> " Nothing splendid has ever been achieved except by those who dared > > > believe that something inside them was superior to circumstances." > > > >> > > > >> -- Bruce Barton > > > >> > > > >> On Mar 6, 2013, at 6:18 PM, "ghostfox3"<loretts54@> wrote: > > > >> > > > >> Hello, > > > >> > > > >> I previously posted about crop to photo service changing resolution > > > from 300 ppi to 72 ppi on my images. > > > >> > > > >> Well ... > > > >> I decided to use convert& modify to change tiffs to jpegs ... and > > > the resolution is again changing from 300 ppi to 72 ppi. > > > >> > > > >> How can I rectify this? I have a few hundred photos to crop and > > > convert to jpeg. Again I have looked in all the dialogue boxes I > can think. > > > >> > > > >> I am using version 7.2. Snow Leopard. iMac > > > >> Thanks in advance. > > > >> > > > >> Loretta > > > >> > > > > > > > > > > > > > > > > > > > > ------------------------------------ > > > > > > > > Yahoo! Groups Links > > > > > > > > > > > > > > > > > > > > > > > > > >