Resolution for upload images ??

[armando_m]

I had been uploading the photos after resizing them, no changes in the resolution

One of the particular photos look blurry after uploading it:

the blur is more apparent at the scratches on the red paint of the stop sign

After changing the DPI from 300 to 72 the uploaded image looks ok


Is there anything else that needs to be done to a jpg image before uploading it to the web so it is displayed with the best quality ?

TIA

[OldClicker]

DPI makes no difference as a digital. I think that when you change the 'DPI", you are also changing the jpg compression or 'Quality' somehow. What software are you using to downsize? How did you change from 300 to 72? - TF

[Photo-John]

Going way back here - this is one of the first articles to appear on PhotographyREVIEW.com. I think we actually launched with it in 1999

The article is a bit dated now (you'll notice it refers to scans!), but the basic principles are still the same.

How To Make A Good JPEG

By the way, the resolution setting in your software makes no difference for an image you display on the Web. The Web display resolution is controlled by the browser (Internet Explorer, Firefox, Chrome, etc.). Whether Photoshop says the resolution is 72 dpi or 300 dpi, your images will display at the same size on this site. And that size is the actual pixel dimensions. The only numbers you should be looking at when resizing are the pixel dimensions of the image. I am currently sizing my Web images to just under 800 pixels on the long dimension. That's a good size for quick loading and it works well with most forum and gallery site layouts.

[armando_m]

I use Capture NX2 to do the PP and also to save the images as JPG.

There are options to set the size , dpi which if change also changes the size of the image , quality (jpg compression), finally and option to resample the image or not, I do select resample, I have not seen much difference in selecting resample or not resample.

I understand the DPI only is supposed to make the image to be displayed larger or smaller.

I was puzzle to see that if I merely adjusted the size and left the DPI at 300, the quality was degraded after uploading to the web, the same happens if uploaded here or to imageshack without the resize option.

If I resize the image with the microsoft power toy, I see the same degradation in quality.

Anyway, after all this rambling, I'll follow the steps listed in the post that Photo-John shared

Thanks !!

[OldClicker]

"I understand the DPI only is supposed to make the image to be displayed larger or smaller."

Just to clarify - as a digital, Dots Per Inch (DPI) does not make the image larger or smaller - it does nothing. The only time it matters to most of us is when it is printed.

The size (1024 x 768) of the two you show above did not change when you went from 300 to 72 DPI.

Did you actually change the first image above or did you go back and resize the original?

TF

[freygr]

For web display, DPI has no meaning. The size does, you want the image to file the screen but the image has to be smaller than the display size. As the display size has increased over time. Windows XP min resolution is now 800 by 600, with most current computers and laptops 1024 by 768 is the display resolution but for wide screen 1280 by 768 (or 800) and up.

You also need small file sizes for quick load times, and the king of compression is the PNG, but JPG also works but you need more access to the compression setting than most programs will give to get optimum results.

[livin4lax09]

photoshop's save for web is a great feature that can help to quickly cut down file size and keep the image looking nice.

[armando_m]

"I understand the DPI only is supposed to make the image to be displayed larger or smaller."

Just to clarify - as a digital, Dots Per Inch (DPI) does not make the image larger or smaller - it does nothing. The only time it matters to most of us is when it is printed.

The size (1024 x 768) of the two you show above did not change when you went from 300 to 72 DPI.

Did you actually change the first image above or did you go back and resize the original?

TF

Well, perhaps capture nx2 has a bug

I resize by clicking Edit and Size/Resolution
and shows me this dialog


On the first image, starting from RAW , I changed the size to 1024x768, the program left the DPI field at 300, but changes the dimension in inches, as shown here:

Image is then saved as JPG with 80% quality.
Uploading this version caused the blurr. The JPG looks fine in my computer.

Second image, starting from the original RAW, I changed the DPI from 300 to 72, this time the program changes the dimension of the image close to 1024x768, but dimension in inches is left alone.

Saved as jpg with 80% Quality, this one does not have the blurr problem after uploading to the web.

[armando_m]

photoshop's save for web is a great feature that can help to quickly cut down file size and keep the image looking nice.

I looked for this on nx2 and can't find it ...

[OldClicker]

I'm still looking.

IMO, you can forget 'Save for Web' since it strips the EXIF data that I think is valuable for images posted here on PR. It also gives you less options.

Your first image is hosted on Imageshack and the second is hosted here on PR. My bet, so far, is that Imageshack is further processing your image.

To give it a fair try:

- Open the RAW image in NX2.
- Click Edit>Size/Resolution.
- Set the width pixels at the bottom to 1024.
- Apply
- Save the image as Filename_300.jpg at 80% Quality.

- Re-open the RAW image.
- Click Edit>Size/Resolution.
- Set the Resolution to 72 DPI
- Then set the width pixels at the bottom to 1024.
- Apply
- Save the image as Filename_72.jpg at 80% Quality.

Post both here using PR as the host.

TF

[armando_m]

you're correct image shack seems to be doing something extra to the jpg file

both are now in PR resized to 1024, and now both files look good

here is the 300dpi


and the 72 dpi


Thanks for your help