Luminous Landscape Forum
Raw & Post Processing, Printing => Digital Image Processing => Topic started by: Justan on December 05, 2009, 12:03:29 pm
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A couple of days ago I exported a PSD file to create a reduced size JPG. I did this by doing a save as and selected JPG . The save as was done full size, max quality. After that I reduced the jpg image by about 2/3rds and saved it again.
The result was not only was a lot of the color range lost but the image lost most of its nuances.
How do others do this conversion and maintain the qualities of the original?
The goal of this process is to make smaller scale images, which closely resemble the original, but are suitable for web based viewing.
BTW I'm using CS3.
TIA!!
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A ) Ideally, you wouldn't re-save jpegs ... jpegs should be the end of the line ... so make all jpegs from the PSD. Jpegs are compressed and re-compressing a compressed image isn't a great workflow.
B ) Are you sure there wasn't some kind of color space issue on the second re-save? JPEGs for the web HAVE to be in sRGB.
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The real problem here isn't as much re-saving the JPEG (agreed not best practice because it is lossy), but more fiundamentally the whole workflow. You want to make as many of the necessary adjustments as possible in a 16 bit wide gamut colour space BEFORE saving the image as a JPEG. And you also want to convert the Mode from 16 to 8 bit after doing as much as poosible in 16 bit.
So here's a workflow approach which works well:
(1) Open the PSD and leve it in 16 bit ProPhoto for now.
(2) Resize the image with resampling selecting the PPI and pixel dimensions you want (96PPI is a decent average for most contemporary displays) and maximum dimension of 800 pixels will work for many. Make sure the resampling method is set to BICUBIC SHARPER.
(3) Go to Edit>Convert to Profile, select sRGB as the destination space and make sure Black Point Compensation is checked. This is vital.
(4) Go to Edit>Mode and select 8 bits per channel.
(5) Go to File> SAVE AS, select JPEG and set the quality to 10 or 11 (unless you and your recipients don't mind the larger file size which comes with 12).
If you are doing many of these you can make an Action of the process.
Try it this way and let us know whether there is an improvement in the matching between the JPEG and the PSD you started with. Should be.
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Before
(http://www.explore-greenwater.com/pix/3NovemberMonelk.jpg)
After
(http://www.explore-greenwater.com/pix/5NovemberMonelk.jpg)
These are larger than suggested, with apologies to those like myself with slow broadband.
Note that I also reduced a brush filter opacity fill by about 50% between the first and the 2nd (the effect was over done in the first one but it took me a while to realize it).
There is much greater color fidelity compared the original.
And about 2/3rd the bytes of the first example.
There is one minor correction - you wrote:
4) Go to Edit>Mode and select 8 bits per channel.
With CS3 Mode is under the Image menu.
~~Thank you very very very much~~
Your notes will get tacked to the wall at least until I memorize the process.
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Yes - thanks - Mode is under the Image menu - a senior's moment.
The cool alternative to tacking the notes on the wall is to make an Action of the steps. Even making an Action you can stop the process at whatever step you wish by tagging a stop point to the left of the step in the Action where you think you may wish to intervene manually.
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Thanks! I’ll definitely look into making an Action as I get closer to doing this for a batch of images
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The result is much, much, much improved!
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For sure.
And one step I forgot to mention - because often I don't find it all that necessary for web images - is output sharpening as the FINAL touch after all else is done. But great care is needed to not overdo it. PK Shapener has dedicated web-oriented sharpeners which work very well - in fact when I do use it I often dial-down the opacity of the layers to keep it discrete.
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Thanks for the tip about output sharpening. I started playing with high pass a few weeks back & delight at the result it brings out, but haven’t looked into other sharpening tools. Per your note I (today) found an intro guide (http://www.layersmagazine.com/photoshop-output-sharpening.html)on some sharpening techniques.
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If you don't use PK Sharpener, High Pass technique within Photoshop is a good alternative. For prints in particular, where very high-quality sharpening is really important, I prefer PK Sharpener Pro - it's a first-rate specialized plug-in, well worth the (reasonable) price.
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The result is much, much, much improved!
The credit goes to Mark. Well that, and a couple of people who were less than thrilled with the effects of the brush filter I (over) used. A classic case of finding a new toy and promptly miss-using it.
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If you don't use PK Sharpener, High Pass technique within Photoshop is a good alternative. For prints in particular, where very high-quality sharpening is really important, I prefer PK Sharpener Pro - it's a first-rate specialized plug-in, well worth the (reasonable) price.
Thanks once again, Mark! You comments are understated and very rich!
I didn’t know about converting to 16-bit files until I read your comment yesterday.
I found the PixelGenius site and will check out PK Sharpener when I have some time.
Converting to 16-bit files brings up a question: I typically export my PSD to a tiff file for printing with Qimage. Given this process, do I need to convert the 16-bit image to an 8-bit file before creating a tiff file?
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Thanks once again, Mark! You comments are understated and very rich!
I didn’t know about converting to 16-bit files until I read your comment yesterday.
I found the PixelGenius site and will check out PK Sharpener when I have some time.
Converting to 16-bit files brings up a question: I typically export my PSD to a tiff file for printing with Qimage. Given this process, do I need to convert the 16-bit image to an 8-bit file before creating a tiff file?
Thank you Justan - glad the comments are helpful.
Now, let us go back to square-1 on the PSD files: where do they come from? What camera are you using, and does your image start life as a raw file or something else? The place to get into 16-bit Mode and a wide gamut colour space is at the raw image stage from the raw converter. If the file has already been rendered (from the raw converter) as an 8-bit image, converting the Mode to 16 bit will not be helpful. If your images start life in a wide colour space such as ProPhoto RGB, they should anyhow be in 16-bit mode. 8-bit images often don't perform well in a very wide gamut space such as ProPhoto. The idea of starting from the raw image in ProPhoto 16-bit is that once you render this file into a three-channel 16-bit ProPhoto RGB image, you will have the maximum amount of data available for subsequently re-purposing the image any how you want it, be it for small prints, large prints or the internet.
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I wondered about that. The camera is a Nikon D80 set to create raw (.NEF) files. Photoshop Bridge says that they are 8-bit files
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I wondered about that. The camera is a Nikon D80 set to create raw (.NEF) files. Photoshop Bridge says that they are 8-bit files
Bridge is probably saying that because your default Camera Raw setting (if you are using Camera Raw or Lightroom) is set to 8-bit. You should be able to change the default to 16-bit.
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I didn’t see an adjustment in Bridge, but once set to 16-bit under Mode in Photoshop, when I tell Bridge to open an image in camera raw (^-R) it shows up in camera raw as 16-bit
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...according to my camera manual, the RAW files created are compressed 12-bit images...
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Yes, the raw files are 12 bit, but the image files get converted to 16 bit when you specify 16 bit in Camera Raw.
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Thanks.
Back to my previous question - will I need to convert these to 8-bit prior to doing a Save-As to create a Tiff from the original?
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Converting to 16-bit files brings up a question: I typically export my PSD to a tiff file for printing with Qimage. Given this process, do I need to convert the 16-bit image to an 8-bit file before creating a tiff file?
If you are using QImage, I believe that you can print directly from your 16 bit PSD file. I do know that QImage will print from 16 bit layered TIFFs (which is what I do, using Win XP, Epson 2400 printer). I believe that QImage converts the file to 8 bit on the fly for printing.
Paul
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Since you are going for images that are suitable for web viewing, you might try "save for web and devices" in Photoshop. This is what I use. Take your 8-bit PSD, convert it to sRGB, re-size to your site specs, add adjustment layers to boost the contrast and saturation, and then do a "save for web and devices." Adjust quality to compress the image so your site is fast. The point of the preview window is to replicate what the image will look like in a web browser.
Hope this helps.
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That should be right - but I'm not a Q-Image user, so I'll defer to Q-Image users on that aspect.
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If you are using QImage, I believe that you can print directly from your 16 bit PSD file. I do know that QImage will print from 16 bit layered TIFFs (which is what I do, using Win XP, Epson 2400 printer). I believe that QImage converts the file to 8 bit on the fly for printing.
Paul
Thanks!
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Since you are going for images that are suitable for web viewing, you might try "save for web and devices" in Photoshop. This is what I use. Take your 8-bit PSD, convert it to sRGB, re-size to your site specs, add adjustment layers to boost the contrast and saturation, and then do a "save for web and devices." Adjust quality to compress the image so your site is fast. The point of the preview window is to replicate what the image will look like in a web browser.
Hope this helps.
I used the Save for Web feature in the past, but didn’t do some of the additional steps you noted. The quality reduction I experienced due to Save for Web lead me to see if there is a way to minimize the changes that need to be made. But I will definitely try the steps you mentioned. I haven’t tried converting to sRGB before.
Thanks!
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Hi Justan-
Yep, that's the point. Your photo will probably look awful in photoshop after you have added contrast and saturation, but then look good when you click save for the web. If you want to test it, just open the saved file in a few different web browsers to see how it looks.