david.atwell

DPI and YOU - Understanding Resolution for Print and Web

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Well, I'm not going to sticky my own tutorial. Another mod is welcome to if they think it's worthy, though.

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"work as big as possible" Does this also apply to cropping digital photos when doing basic editing ? Should you crop, along with resizing, as the last steps ? Is there a correct, or better sequence to photo editing ? My usual routine is : Open jpeg from point and shoot; save as a png; crop; adjust brightness, contrast, saturation; resize and save depending upon what I want to do with it. Is that correct ? Thank you.

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I tried to get the recommended downloads, but got only to FORUMER with a 404 error message for all the links you gave. :sad:

Am I doing something wrong? I really am very confused by the abilities of Paint.net. I can do the simple things, and Paint does improve my photos a LOT!

I need to be able to change a color of a pashmina (shawl) which has folds. I am working with everything I can find here, but am not getting too far. :roll: I do Searches with varying results. Perhaps I am using the wrong verbage.

I think your tutorial is great. I just wish it could help me. You get an A+!! It clarified a couple of things for me!!!

Pat :D

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We recently moved our forum, so the old links don't work. I'll PM David about updating the links in this thread, and I'm glad it helped you. :)

Regarding the shawl, the Hue and Saturation  adjustment, or possibly the Conditional Hue and Saturation Plugin might help you.

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I have used the Hue and Sat very successfully. With this tutorial and some more practice, I think I will be on my way. :music:

I did try to Search for "Colour Balance" in this Forum, and will try again. There was no 'Colour Balance' that I could find. :/

Thanks for your response.

Pat B)

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pat71896,

Color Balance is part of BoltBait's plugin pack.

Color Balance + is part of dpy's plugin pack.

---------------------------------------------

Both plugin packs are pinned on the first page of the plugin forum.

Edited by Sarkut

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Thanks, pyro. I was in the middle of the semester from hell...made it rather difficult to clean up my mess. :-P

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I'm really struggling with this - when I do as you say, create the image large, and then cut it down by halves, I still get a really poor-quality image. It looks great on my own computer, whether in paint.net or in the image viewer after saving the file, but when I put it on the web, it looks terrible. See the logo on this page:

http://www.facebook.com/pages/Invoc-Houston-CRM-and-BPOS-Solution-Provider/208352115165

Can you tell what I'm doing wrong?

Thanks!

Andy

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So how would 'working large than shrink it down' actually make the image appear cleaner or less pixelly?

For example say you are drawing a face, and for all intents the face has a width of say an inch on your screen. If you draw it normally, you will have pixels that are apparent, but say you make the canvas 4x as large, draw it, and then shrink it to the 1 inch size, the pixels are still going to be there.

What am I missing here? I want to do lineart, but I cant escape from ultimately having my picture look pixelly. I fully understand that on a bigger canvas you indeed can put 'more detail' into it, but as soon as you shrink it to your desired size, all that details goes away because there is the limit to pixels and they will just get blended to form the smaller size.

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What am I missing here? I want to do lineart, but I cant escape from ultimately having my picture look pixelly. I fully understand that on a bigger canvas you indeed can put 'more detail' into it, but as soon as you shrink it to your desired size, all that details goes away because there is the limit to pixels and they will just get blended to form the smaller size.

The answer to that question is control.

On a larger canvas controlling line art is a lot easier as there are more pixels dedicated to drawing your lines. If you attempt to draw the same lines on a smaller canvas you ultimately have less pixels to play with. When the larger canvas is reduced in sized the shape of the line art remains without the pixellation, whereas if you begin to draw your line art on a small canvas you start with pixellation from the outset which takes a lot of hard work to get rid of thereafter through things such as blurring, feathering, etc.

circle500x500.png

The line art is drawn above is at 500x500 pixels. It is crisp and clean and I have control over it in terms of more pixels to play with.

circle500x500reduced.png

Above it is reduced to 250x250 pixels and I have no control over it as the circle spans far fewer pixels. It is however still nice and crisp~ If I increase the size back to 500x500 (below)I end up with a blurred circle.

circle250x250enlarged.png

I hope this helps answer your question as to why it makes logical sense to begin with a canvas which is as large as possible.

With regard to starting on a large canvas and still ending up with a pixellated end result, there are many ways to fix that. Ultimately, in order to control your lines you need to disable antialiasing which eliminates blurring and feathering and gives crisp and clean lines (and highlights pixellating). When you are finished with your line art, you can then blur and feather, or blur and apply plugins such as AA's Assistant. Masking is also extremely useful...

Cheers,

Edited by ventor1

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@ David.Atwell That was an excellent tutorial above. I needed something down to my level and this I could understand. I am new to editing images and having a hell of a time and time is running out. Long story short as I have already posted in another post, but I have either 7 days left to figure out what to do with 750 images I downloaded from a very expensive subscription from one of the premier photo stock companies.

I was or rather in the midst of having a devil of a time "shrinking" the pics without massive detail loss and clarity. If I could settle with these resized images I would of stolen all my pics fair and square off of Bing Images, vs. paying hundreds of dollars for super high resolution.

I am questioning now your theory that bigger is better. I have till now been downloading super sized images of the greatest clarity. But when going from 300 dpi at say 3000 by 2000 down to 300 by 200 you loose lots of detail. In fact, I found out you have a far superior image if you start out with only 72 dpi at 450 by 300 and go down to 300 x 200. It would suggest that the less distance one has to re-size a photo the less "noise" goes into the photo. So working on a super high resolution, extral large size photo has proven so bad I am now frantically thinking seriously of re-loading all 750 photos in the 72 dpi that start off a much smaller size. In fact for the web as their final destination wouldn't the web pages load faster with the 72dpi? You are saying we can not later go back up from 72 to 300 is that correct? I think that is what you are saying in the tutorial.

It is plausible as I am new to all this that I am not even comparing apples with apples and we are speaking of two differet subjects or applications. How the photos react going the opposite way from small to large I have no idea, just the large to small.

They [stock photos] are all coming in JPEGs and I can resave them in PNG on my computer, though when I do this IMMEDIATELY the loss of quality is apparent. Any work arounds for this? Or how do I go from super large to small without the degradation of quality?

Edited by Get A Trip

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I was or rather in the midst of having a devil of a time "shrinking" the pics without massive detail loss and clarity. If I could settle with these resized images I would of stolen all my pics fair and square off of Bing Images, vs. paying hundreds of dollars for super high resolution.

Careful doing that. You can wind up getting yourself sued that way. :-) I recommend commons.wikimedia.org for free images; you can also do an advanced search on flickr.com.

I am questioning now your theory that bigger is better. I have till now been downloading super sized images of the greatest clarity. But when going from 300 dpi at say 3000 by 2000 down to 300 by 200 you loose lots of detail.

I think you missed the part about how DPI doesn't matter until you're printing. :) Yes, you lose lots of detail. That's just the nature of resizing. It's like saying that if you tear out half the pages of a book, you don't get the whole story. Of course not; the information is gone.

In fact, I found out you have a far superior image if you start out with only 72 dpi at 450 by 300 and go down to 300 x 200. It would suggest that the less distance one has to re-size a photo the less "noise" goes into the photo.

Untrue. Now, this will make the final image more similar to the original, but not superior to starting from a high resolution image. Think of it this way: you can always take information away, but you can never add back in information that wasn't there to begin with.

In fact for the web as their final destination wouldn't the web pages load faster with the 72dpi?

Nope. Takes exactly the same amount of time to load. You need to reread the tutorial. :) Web browsers roundly ignore DPI information in images. Remember, I have an image in the tut at almost 15,000 DPI, and it loads at exactly the same speed as the images next to it.

You are saying we can not later go back up from 72 to 300 is that correct? I think that is what you are saying in the tutorial.

Never said that. You can change the DPI all you want; it's the resolution you can't increase without significant quality loss.

They [stock photos] are all coming in JPEGs and I can resave them in PNG on my computer, though when I do this IMMEDIATELY the loss of quality is apparent. Any work arounds for this? Or how do I go from super large to small without the degradation of quality?

JPEGs are lossy images. PNGs are lossless. I don't know why you're saying that seeing them as PNGs results in quality loss. That makes no sense. As for going from super large to super small - as I said above, you're definitely going to lose quality. There's no workaround. All small images are going to be lower quality than a large image in the same format. It's a fact of life on the computer.

Anyway, glad you liked it. Read it again. :)

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so now I have some complex QR code images (look like the attached) in 450x450px which I need to resize each of them to 60x60px. I've tried the "resize" option (with different sampling method) but I either get a blurred image or a sharp image but with the dots not quite at the right place. What do you think?

post-91640-0-83043800-1346227408_thumb.p

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Hi there 357h3r, welcome to the forum.

This is not strictly a DPI issue, so please repost your question in the Paint.NET Discussion & Questions section of this forum. Thanks.

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nitenurse79 - I'm glad you found this useful!

 

So, I'm going back through and reexamining my old tutorials to make sure nothing needs to be updated.  Are there any burning questions anyone happens to have about DPI (either in general, or as it relates to PdN in particular)?  I might do an updated version in the not-so-distant future.

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David,

 

Did you really take a year to reply to nitenurse79?

 

I read this post, while searching for 'converting other image types to vector images', very interesting.  So informative and entertaining, a little life altering; I thought I was reading a Max Lucado book. 

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