Posted: Thu Mar 19, 2009 6:22 am Post subject: Questions about retaining quality of JPG image for editing
I have a JPG image that I want to edit with photoshop 7. I know that if I edit directly the JPG image and save again as new JPG image, the quality of the new saved image will be degraded. Experienced user know that because JPG is a lossy format.
I want to retain the quality of the edited image. Then I heard that the TIFF format is a lossless format that support compression.
I usually done this:
A. Let's say I have a JPG image that I want to edit, then I open the image and directly save it as a new TIFF image (with LZW compression).
B. Then I will do editing to the TIFF image.
C. After the editing TIFF image done, I will save it as a new copy of JPG image.
Note: Step C is only performed if I want to publish the image.
The questions:
1. Is the step A a correct step from the view of experienced user? I mean is this a step that I should do if I want to retain the quality of the want-to-edit image.
2. Does the LZW compression in TIFF give a quality loss in the image?
3. If I save a JPG image in TIFF format (with LZW compression), is there any quality loss (i.e., artifacts) in the saved TIFF image?
The next question is about saving the image as JPG in maximum quality for publishing.
Usually I choose these settings in the JPEG options:
* I choose "12" for the quality (the highest number).
* I choose "Baseline optimized" in the Format Options (There are 3 options available: Baseline ("Standard"), Baseline Optimized, and Progressive).
The questions:
- In save as dialog, there is "ICC Profile" checkbox. What is it used for? Does it affect the quality of the image? Should I check this option if I want to gain maximum quality image?
- Am I choose the correct option in the Format Options if I want to gain maximum quality image? What's difference of the three Format Options? What should I choose if I want to gain maximum quality of the JPG image?
- Is there any other factor that I must consider if I want to gain the maximum quality of the JPG image?
Sorry, if my english is very confusing since I'm not english speaker.
Thanks in the advance.
Last edited by mrribbit on Fri Mar 20, 2009 12:57 am; edited 4 times in total
Joined: 20 Dec 2008
Posts: 710
Location: Oklahoma PS Version: photoshop cs5 OS: win7 pro 64 bit, i7-3.2g, GTS 450,
Posted: Thu Mar 19, 2009 7:59 am Post subject: Re: Questions about retaining quality of JPG image for editi
hi,
I hope some one with indepth knowledge replies to you I am always interested in these formats and which is the best and i have done a lot of reading on this.....
1. if your using photoshop.... why not save it in the psd format for pre post and editing ? unless your looking at using the tif file in other editors. otherewise, psd , to me would be thebest ..
2. tiff format , main advantages with tiff format, it is widely used in various software, file compression not that great but can have multible layers ...
3. the lzw compression, does best when there are repetive pixals, like with b/w or relative few colors..... the file size , if the image is complex you can actually an increase file size... smilie...
4. jpg .... even with the hi quality setting it possible to get artifacts....
if using photoshop.... my work flow is
1. i save my work in psd format...... if i am planning on doing multible editing sessions with the image...
2. when finish with any editing and am looking at storage,etc I choose either png or tiff uncompressed ... , with tiff i use the lzw if i need to be concerned about file size ... or compatiblity of the lzw with certain programs... also i preferr png but if i need layers then i go with the tiff ..
3. the use of the jpg format... if quality is important and you need to use it.. then definitely going to a 12 .. however, now maybe it just me but even at 12 there can be artifacts..... I generally, in photoshop, will go to the menu, and select "save for the web" for jpg there alittle bit more control over on how much compression, you get a preview, you can apply blur (if there artifacts showing) , matt (haven't really check that out yet if it usefull for me)
also in that box... there a checkbox for optimized.... this will result in a littlbe smaller files size... but you run the risk of compatibility when used in other programs...... i can't say how big of an issue that is or not but it something to be aware of....
now the question about icc profile, I am not really good enough to reply to that....... to me.. icc profile comes into play when dealing with output device such as printers .... although I think if your saving with the srgb ... may not need the icc profile..... but get some one else opinion on that for sure..
mrribbit wrote:
I have a jpg image that I want to edit. I know that if I edit directly the jpg image and save again as new copy image, the quality of the new saved image will be degraded. Experienced user know that because jpg is a lossy format.
I want to retain the quality of the edited image. Then I heard that the .tiff format is a lossless format that support compression.
I usually done this:
A. Let's say I have a jpg image that I want to edit, then I open the image and directly save it as a new tiff image (with LZW compression).
B. Then I will edit the tiff image.
C. After the editing tiff image done, I will save it as a new copy of jpg image.
Note: Step c is only performed if I want to publish the image.
The questions:
1. Is step A is a correct move from the view of experienced user? I mean is this a step that I should do if I want to retain the quality of the want-to-edit image.
2. When saving as tiff format, is choosing LZW compression is a correct decision?
3. Is the tiff image and original jpg image will still have same quality? I mean is there any quality degradation in tiff image if compared to original jpg image?
The next question is about saving image as jpg format in maximum quality.
Usually I choose this setting in JPEG options when saving as jpg format for maximum quality:
* I choose "12" for the quality (yes, it's the highest number).
* I choose "Baseline optimized" in the Format Options.
The questions:
1. In save as dialog, there is "ICC Profile" checkbox. What is it used for? Does it affect the quality of the image? Should I check this option if I want to gain maximum quality image?
2. Am I choose the correct option in the Format Options if I want to gain maximum quality image? What's difference of the three Format Options? What should I choose if I want to gain maximum quality of the jpg image?
3. Is there any other factor that I must consider if I want to gain the maximum quality of the jpg image?
Sorry, if my english is very confusing since I'm not english speaker.
Thanks in the advance.
1. if your using photoshop.... why not save it in the psd format for pre post and editing ? unless your looking at using the tif file in other editors. otherewise, psd , to me would be thebest ..
Yes, I'm using photoshop.
I use TIFF because it supports compression, while PSD doesn't. Currently I have a space issue so I prefer TIFF than PSD. I used to use BMP format until I found out about TIFF. But I must admit that saving in PSD is more faster than saving in TIFF+LZW.
Quote:
2. tiff format , main advantages with tiff format, it is widely used in various software, file compression not that great but can have multible layers ...
So, that means there is other format with better compression than TIFF. Could you tell me what is it?
Quote:
3. the lzw compression, does best when there are repetive pixals, like with b/w or relative few colors..... the file size , if the image is complex you can actually an increase file size... smilie...
Since so far I don't know other lossless format which has better compression than TIFF+LZW, I don't think I have problem with this issue.
Quote:
4. jpg .... even with the hi quality setting it possible to get artifacts....
Yes, of course. It's clear that because JPG is a lossy format. Before I knew about lossy and lossless concept, many my works had suffered quality loss ~_~.
Quote:
1. i save my work in psd format...... if i am planning on doing multible editing sessions with the image...
What is the multiple editing sessions? What is it used for?
Quote:
2. when finish with any editing and am looking at storage,etc I choose either png or tiff uncompressed ... , with tiff i use the lzw if i need to be concerned about file size ... or compatiblity of the lzw with certain programs... also i preferr png but if i need layers then i go with the tiff ..
If you want to edit again the file, are you going to save back to PSD?
I prefer to save the image in a same format whether for editing or not.
Quote:
3. the use of the jpg format... if quality is important and you need to use it.. then definitely going to a 12 .. however, now maybe it just me but even at 12 there can be artifacts..... I generally, in photoshop, will go to the menu, and select "save for the web" for jpg there alittle bit more control over on how much compression, you get a preview, you can apply blur (if there artifacts showing) , matt (haven't really check that out yet if it usefull for me)
* Yeah, I realize there is the "Save for the web" menu. But usually I don't use this because I prefer the simple dialog from "Save as" menu. But thanks anyway to remind me of this.
* I'm also not too understand what does the matte used for, I hope someone can explain this.
Quote:
also in that box... there a checkbox for optimized.... this will result in a littlbe smaller files size... but you run the risk of compatibility when used in other programs...... i can't say how big of an issue that is or not but it something to be aware of....
Yeah, I know that, but until now I never meet this issue.
Could you give me examples of the program that cannot read optimized JPG image well?
To view image, I use ACDSee 3. So far, it doesn't have a problem to view optimized JPG image. And today popular modern browsers like IE, firefox, and opera can view optimized JPG image as well.
I need you to answer this question:
If I save the JPG image in TIFF format (with LZW compression), is there any quality loss (i.e., artifacts) in the saved TIFF image? Just answer with yes or no.
Joined: 24 Sep 2007
Posts: 3515
Location: Haverhill, UK PS Version: Lightroom 5, CS4 & Elements 11 OS: Windows 8.1
Posted: Thu Mar 19, 2009 12:07 pm Post subject:
Yes. But only from the file being saved previously in JPEG. Apart from that, TIFF+LZW is lossless and therefore does not introduce any additional compression artifacts.
Great reply by the way Jerry, some great information in there.
The matte option is only applicable if saving an image with transparent pixels in it. Because JPEG does not support transparency, the matte colour you choose will replace the transparent pixels.
From my experienced, baseline optimized is the way to go. Has been for quite a few years.
Here's some information on color profiles from the Adobe website-
For ICC profile, to make it simple, just answer this questions:
* Is ICC profile affect the quality or appearance of the image?
* "ICC Profile" checkbox in "Save As" dialog ... should I check this option? How about youself, do you usually check this option too?
I also heard about Smart Object feature in photoshop CS2 above. Is using Smart Object will achieve same goal as saving original JPG to TIFF before editing?
Let's say I have a JPG image that doesn't have a profile inside it. How to embed or change a profile from the JPG image without doing save as?
Quote:
Yes I'd recommend it, it's always a good idea to save the profile along with the file.
I heard some people said Adobe RGB 1998 profile is the recommended profile instead of the default sRGB profile, is this true?
Since in this article:
http://www.gballard.net/psd/saveforwebshift.html
It said: "NEVER put Adobe RGB (1998) aRGB on the internet — aRGB is one of the worst profiles or color spaces to use if you don't understand it."
RECOMMENDED PROFILE SETTINGS IN PHOTOSHOP 6/7/CS
Go to Edit -> Color Settings
Under "Working Spaces" select:
RGB: Adobe RGB (1998)*
CMYK: US Web Coated (SWOP) V2
Greyscale: Greyscale - Gamma 1.8
Spot: Dot Gain 20%
In "Color Management Policies" select "Preserve Embedded Profles" for "RGB", "CMYK" and "Gray".
This ensures that if an image is opened that was created in a different working space, the original colour information and
working space tag* is retained, rather than being converted automatically to the current working space.
Remember that when an image is "converted" from one working space to another then the colours in the image are altered.
This is done so that the image after the conversion resembles the way it appeared under the original working space.
You may want to avoid this conversion under certain circumstances. These circumstances are explained later in this document.
Also in "Color Management Policies" section tick "Ask When Opening" for "Profle Mismatches". Leaving the tick box blank for
the "Missing Profles" option ensures that any image without an embedded profle will open automatically in the working space
selected above.
Tick the "Advanced Mode" option at the top left of the Color Settings window.
Under "Conversion Options" select "Adobe(ACE)" as the Engine and "Relative Colormetric" as the "Intent".
Ensure that "Black Point Compensation" is not ticked.
Do not select any of the Advanced controls.
Is the above article correct? Should I follow the settings from the article?
Could you give me a suggestion for the "Color Settings"?
Is the "U.S. Prepress Defaults" setting a good choice?
Last edited by mrribbit on Sun Mar 22, 2009 3:52 am; edited 3 times in total
Joined: 24 Sep 2007
Posts: 3515
Location: Haverhill, UK PS Version: Lightroom 5, CS4 & Elements 11 OS: Windows 8.1
Posted: Mon Mar 23, 2009 8:27 am Post subject:
mrribbit wrote:
I also heard about Smart Object feature in photoshop CS2 above. Is using Smart Object will achieve same goal as saving original JPG to TIFF before editing?
Not sure what you mean here. Smart Objects can not be saved inside a JPEG, so you'd still have to save as a TIFF or PSD anyway. Smart Objects are more for helping you keep your Photoshop workflow non-destructive, and whilst I'd always recommend them, they are limited somewhat. Not all your edits can be applied to smart objects, ie painting.
Colour management is a lot about finding a workflow that works for you. If you talk to 5 experts, you'll probably hear 5 different ways of working. This article deals with saving graphics for the web, I thought you were asking about your personal photo collection (that you were looking to print some day). As far as I know, most web browsers still do not support colour managed files, so until that's addressed there really is no need. If you're exporting graphics for a website then I agree, no need to save ICC profiles.
mrribbit wrote:
I heard some people said Adobe RGB 1998 profile is the recommended profile instead of the default sRGB profile, is this true?
Since in this article:
http://www.gballard.net/psd/saveforwebshift.html
It said: "NEVER put Adobe RGB (1998) aRGB on the internet — aRGB is one of the worst profiles or color spaces to use if you don't understand it."
Generally speaking, SRGB is a good multi-purpose introdutory level colour profile. Adobe RGB hasa wider gamut of colours so is used more in line for people wanting to print their work. Adobe RGB is respected by many Photoshop users and photographers and is widely used and supported.
mrribbit wrote:
Is the above article correct? Should I follow the settings from the article?
Could you give me a suggestion for the "Color Settings"?
Is the "U.S. Prepress Defaults" setting a good choice?
Like I said, there really is no 'correct' settings but they seem like sensible, good settings to me. The 'US Prepress setting should be fine if you live in the US. _________________ Matt
3photoshop.com
http://www.3photoshop.com
About color settings, after doing comparison between Adobe RGB 1998 and sRGB, I think I will stick to sRGB since it looks more pleasant to my eyes. So I will choose the "Web Graphics Defaults".
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