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Post by jjtrinva on Dec 2, 2016 14:37:31 GMT
I noticed something when converting JPEGs to TIFF before working on them and curious as to what is happening behind the scenes and if anything I should be thinking about.
If I open the JPEG directly, Save as TIFF and then bump up resolution to 300, I end up with a 15.3 x 11.49 inches document (4592 pixels by 3448 pixels) that is roughly 47.5 MB in size.
If I "Process Multiple Files" to convert to TIFF and 300 Resolution (leaving width/height blank and "Constrain Proportions" unchecked) the resulting images are 25.5x19.1 inches (7653 pixels by 5747 pixels) and 132 MB in size.
I guess my concern is whether Photoshop is adding pixels that could degrade the image if I'm choosing a large format photo.
As background, I'm producing a photobook and while most of the pictures are going to be in the 5x7 or so range...a few will be 12x12 for 12x15. I'm near the end and just noticed this, so don't really want to go back and redo all of this...but can do some of the pictures that will be full page if necessary for best quality.
Also, for reference, the original JPEG is 25x19 at 180 pixels/inche (4592x3448 pixels) so I'm generally starting out with a pretty good size image out of a good camera set to record at the highest setting.
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Post by deprosq on Dec 2, 2016 22:10:26 GMT
If I open the JPEG directly, Save as TIFF and then bump up resolution to 300, I end up with a 15.3 x 11.49 inches document (4592 pixels by 3448 pixels) that is roughly 47.5 MB in size. Also, for reference, the original JPEG is 25x19 at 180 pixels/inche (4592x3448 pixels) so I'm generally starting out with a pretty good size image out of a good camera set to record at the highest setting. That is the way it should be. In this case the image wasn't resampled. It was just resized for printiing. If you increase the ppi to 300 without resampling your new dimensions should be 4592/300 = 15.3 inches which is what you say you got. In this case you are increasing the ppi AND resampling. If you resample the image to 300ppi your new domensions should be 4592 x 300/180 = 7653 which is what you say you got. Bear in mind that whenever you RESAMPLE to a larger ppi you are creating new pixels and so depending on the size of the increase in ppi the more noticeable any image degradation will be. PPI is mainly used for printing purposes. It has no significance for screen display. Only the actual pixel dimensions and not the ppi determine the size of the image on a screen. When playing with the ppi parameter, you should always have 'resample' unchecked. This way you are only resizing the image physical dimensions for printing without changing (adding/deleting) any pixels. Side Note: it is generally accepted that you should have a minimum of 300ppi to make a good quality print. Therefore, if your original image's pixel dimensions are 4592 x 3448 then the rule of thumb max. sized good quality print you could expect is (4592/300) x (3448/300) = 15in x 11.5 inches. If you print the image on a larger sheet of paper WITHOUT resampling you migt or might not notice any degradation in image quality. The same applies if you print on a larger sheet after resampling the original image. As a general rule, upsampling is not recommended because of potential image quality degradation, but you can treat each image on its merits and try printing on a larger sheet than the "ideal" max. size and see how it looks. The amount of degradation depends to some extent on the contents of the image. |
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Post by jjtrinva on Dec 3, 2016 19:00:33 GMT
Deprosq - Thanks, this is super helpful. Is there a way to automate the process without resampling? I'd love to be able to save a couple of steps where possible.
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nerro
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Post by nerro on Dec 3, 2016 22:11:36 GMT
Deprosq - Thanks, this is super helpful. Is there a way to automate the process without resampling? I'd love to be able to save a couple of steps where possible. Hi jjtrinva and everyone, My name is nerro. I usually post on another forum but my friend Deprosq has sent me an email asking me to reply and help you on his behalf. In the email he tells me that when he now tries to log on to his account, it just continually loops back to the home page with the login prompt and no error mesage. He doesn't know what the problem is with his browser. Anyway, I will try to help. I have read through this thread and I'm happy his post was helpful to you. To answer your question above, unfortunately the short answer is I'm not sure. In the Process Multiple Files dialog box I don't see a Resample Image option to check or uncheck. I see a Resample Image option only in Image > Resize > Image Size. I am not aware of how to automate unchecking any resampling options. Sorry. |
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Post by michelb on Dec 4, 2016 10:27:43 GMT
Deprosq - Thanks, this is super helpful. Is there a way to automate the process without resampling? I'd love to be able to save a couple of steps where possible. Hi jjtrinva and everyone, My name is nerro. I usually post on another forum but my friend Deprosq has sent me an email asking me to reply and help you on his behalf. In the email he tells me that when he now tries to log on to his account, it just continually loops back to the home page with the login prompt and no error mesage. He doesn't know what the problem is with his browser. Anyway, I will try to help. I have read through this thread and I'm happy his post was helpful to you. To answer your question above, unfortunately the short answer is I'm not sure. In the Process Multiple Files dialog box I don't see a Resample Image option to check or uncheck. I see a Resample Image option only in Image > Resize > Image Size. I am not aware of how to automate unchecking any resampling options. Sorry. Simply don't check the 'resize' box. The pixels won't be changed, that's the important factor. Anyway, the compression in tiff is lossless. The 'process multiple files' feature does not offer as many options, particularly the compression method for tiff. Similarly, you can use the 'export to new files' command in the organizer without changing the size (the change is on pixel size, so resampling is automatic if you change that). |
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nerro
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Post by nerro on Dec 5, 2016 0:13:08 GMT
Hi jjtrinva and everyone, My name is nerro. I usually post on another forum but my friend Deprosq has sent me an email asking me to reply and help you on his behalf. In the email he tells me that when he now tries to log on to his account, it just continually loops back to the home page with the login prompt and no error mesage. He doesn't know what the problem is with his browser. Anyway, I will try to help. I have read through this thread and I'm happy his post was helpful to you. To answer your question above, unfortunately the short answer is I'm not sure. In the Process Multiple Files dialog box I don't see a Resample Image option to check or uncheck. I see a Resample Image option only in Image > Resize > Image Size. I am not aware of how to automate unchecking any resampling options. Sorry. Simply don't check the 'resize' box. The pixels won't be changed, that's the important factor. Anyway, the compression in tiff is lossless. The 'process multiple files' feature does not offer as many options, particularly the compression method for tiff. Similarly, you can use the 'export to new files' command in the organizer without changing the size (the change is on pixel size, so resampling is automatic if you change that). Thanks for that michelb. Just a couple of minor things to be aware of with TIFF files. The compression (LZW or ZIP) are lossless but compressed tiff files take more processing to open and close and can be slower to work on. However this extra processing should not be really noticeable on today's fast pc's. One unlikely reason you might not want to compress a tiff file is compatibility with software applications. Both compression methods have been around a long time now so incompatibility should be rare. |
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Post by michelb on Dec 5, 2016 8:14:41 GMT
Simply don't check the 'resize' box. The pixels won't be changed, that's the important factor. Anyway, the compression in tiff is lossless. The 'process multiple files' feature does not offer as many options, particularly the compression method for tiff. Similarly, you can use the 'export to new files' command in the organizer without changing the size (the change is on pixel size, so resampling is automatic if you change that). Thanks for that michelb. Just a couple of minor things to be aware of with TIFF files. The compression (LZW or ZIP) are lossless but compressed tiff files take more processing to open and close and can be slower to work on. However this extra processing should not be really noticeable on today's fast pc's. One unlikely reason you might not want to compress a tiff file is compatibility with software applications. Both compression methods have been around a long time now so incompatibility should be rare. Totally agree. If I may add: the initial post by jjtrinva states: "I noticed something when converting JPEGs to TIFF before working on "
I don't see the point to convert jpeg to tiff BEFORE working on them. The file opened in RAM is the same in both cases. No advantage in quality at all. Of course, when you save your edited image, you get no compression loss if you are using lossless formats like tiff or psd. If one wants both quality and disk space, why not consider opening jpegs in the ACR raw converter? In my case, in 90% of my files, I don't have to do local edits or layers. I simply click on 'Done' and my ACR edits are saved a text in the metadata header of the file witout changing the original pixel values. Of course, I can start from that file which incorpotates 'parametric editing' to create versions with local edits and layers in tiff or psd.
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