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Images: Does Modifying DPI REALLY Have any Effect on Final Printed Outcome
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March 12, 2014, 07:42:25 AM
Here's a question I know Don Cheke could answer right off the top of his head, but I'm opening it up to everyone:

If I use a screen-capture Image-- or an otherwise-acquired Image-- that I've taken into IrfanView or some other Image-manipulation application, and adjusted the Image's DPI (set it to a higher DPI), does this actually result in a higher-resolution, higher-quality Image?

Example:
  • Use IrfanView screen-capture to screen-capture a Google satellite Image of a parcel
  • Depending on which monitor I perform screen-capture within, IrfanView Image Information reports that Image to be 96-110 DPI
  • In IrfanView's ReSize/ReSample utility, I change the DPI to 300, then "Save As..." (JPEG, usually)
  • The size of that Image file increased proportionately, but did the actually DPI and thereby quality of the Image-- when Inserted into TurboCAD-- actually increase? (Loaded/Linked, not Embedded)
My Linked/Loaded (not Embedded) Images in TurboCAD are taking my otherwise ~500KB TurboCAD file and-- when printed to a third-party PDF-writer-- making 10MB PDF files.  Am I causing unnecessarily LARGE PDF files by increasing (tripling) the DPI in an Image-editor before Inserting into TurboCAD?
Is there really any benefit-- in the form of enhanced Image quality-- in doing this, when printing from TurboCAD?  Or am I just adding file size to the Image, and thereby, resultant PDF?

Thanks for any enlightenment/education on the topic.  -Alvin

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Alvin Gregorio
(mostly Residential Architectural 2D; no formal CAD Training; intermittent TurboCAD user since yr. 2000 [ver6.5])
---TurboCAD: V21PP; V20.2PP; V19DL; V11.2Pro; Windows-7-Pro/64-bit; Intel-Core-i3 CPU; 2.27ghz; 4GB RAM; Intel HD Graphics (CPU based)


March 12, 2014, 11:41:51 AM
#1
Alvin

Resampling cannot add more detail. All it does is approximate to smooth out the Pixelation that occurs when increasing the image pixel dimensions.

Depending on what you are doing it is about finding a happy medium of quality/file size.

I would avoid using Jpeg or other formats that use compression as this adds to detail being lost. PNG and BMP seem to be the norm for quality images.

Having images in TC can be problematic and I try not to insert images that are overly large.

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Daz…

V2019 Plat 64bit, Lenovo P72 Laptop, Window 10 Pro for Workstations, Intel Xeon E-2186 CPU @ 2.90 Ghz (6 cores/12 threads), 32GB RAM, 512GB & 1TB SSD's, Nvidia P5200 c/w Max=Q Design GPU, Display UHD 3840 x 2160 pixels
TurboCAD user since V3 and Turbocad 3D V1.


March 12, 2014, 04:11:05 PM
#2
Alvin

Resampling cannot add more detail. All it does is approximate to smooth out the Pixelation that occurs when increasing the image pixel dimensions.

Depending on what you are doing it is about finding a happy medium of quality/file size.

I would avoid using Jpeg or other formats that use compression as this adds to detail being lost. PNG and BMP seem to be the norm for quality images.

Having images in TC can be problematic and I try not to insert images that are overly large.


Thanks for the information Darrel.

For house-- and other buildings-- 2D construction plans, on the Cover/Site-Plan Sheet, I usually have a Parcel Map (from a public on-line source... they store it as a TIFF), a "Vicinity Map" which is usually a screen-capture of Bing Map (streets only, no satellite) or similar, and a Google-Earth or otherwise-acquired Satellite View screen-capture (or "Save Image" from within Google Earth).
  Why do I insert these Images in an otherwise tiny (Bytes-wise) TurboCAD file?:  Because it looks cool! 8)  Trying to set myself apart from the other local architectural-draftspersons, I guess.

I like to start with the Image being as close to as big as I want it in TurboCAD before Inserting into TurboCAD, so that I'm not "spreading out" the pixilation in TurboCAD by scaling the Image larger; do I know if that works or is necessary?... no, I don't.

I basically don't know enough about all the code and whatnot that goes into these Images.  Example:
  In a recent drawing, I used Google Earth to "Save Image" on my laptop monitor, so it was smaller, but a bit higher DPI than my secondary monitor, which is about 96 DPI.
That color Image was 5.25"x8.23"; 96 DPI; and 284KB.
Then, in IrfanView, I resized/resampled it to Grayscale and 20"x31.35"; 300 DPI, which resulted in a file size of 16,784 KB!

The Cover-Sheet/Site-Plan referenced above is shown below.  I ran into an issue trying to Save it larger than 1,000 pixels wide or high, I'll have to post that in the "Problem" board.    -Alvin
« Last Edit: March 12, 2014, 04:22:36 PM by Alvin Gregorio »

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Alvin Gregorio
(mostly Residential Architectural 2D; no formal CAD Training; intermittent TurboCAD user since yr. 2000 [ver6.5])
---TurboCAD: V21PP; V20.2PP; V19DL; V11.2Pro; Windows-7-Pro/64-bit; Intel-Core-i3 CPU; 2.27ghz; 4GB RAM; Intel HD Graphics (CPU based)


March 12, 2014, 06:30:02 PM
#3
I'm certainly no expert on this subject, but I have found that most images I use in TurboCAD (for image wraps) don't have to be that large (I usually use screen captures around 1200 - 1500 px wide by that or something similar in height). All screen captures are 72 or 96 dpi (unless someone has made Windows adjustments to that). If I then save whatever model is wrapped out for use as a image for sharing electronically, I just save as a jpg or png from TurboCAD at a larger size (say 2100 x 3750), but output is still 96dpi. If I need better output for printing or a very good presentation I will output from paper space as a pdf at 300 dpi at whatever size I need. Any print-ready work I need I ensure a higher quality all around.

Technology for up-sizing images has come a long way in the last year or two. Sometimes I require very large images for backdrops in trade show booths, so that may mean 10' x 20' in size. When I need a picture resized (raster image) for this (and printers want at least 100 - 150 dpi for large format work) I have found that one needs a program designed to do this. One such program that I use is Perfect Photo Suite 8. It is designed to up-size without loss of quality. I have used  this several times with exceptional results. I was skeptical at first because the former rule was that it was not possible to do so without loss. You should see what sizes of files one gets with this process, but it is the cost of the need.

Whether the up-sizing in IrfanView or even Photoshop is actually giving a better quality I cannot say for sure, but it doesn't seem to have the quality as I see in Perfect Photo.

I really think that it is all a matter of what the final output and use is. If high quality is going to be required then use high quality all along, but remember that TurboCAD has some limitation. I don't know the actual amount of the limitation but I know I have had to downsize some images for wrapping otherwise they render black or some other solid color.

I don't know if I made any sense here, but this is what came to mind.


March 13, 2014, 02:50:24 AM
#4

Hi Alvin,

it may help to read this . . .

http://www.andrewdaceyphotography.com/articles/dpi/

 . . . and similar articles, or, it may not!  :-\

Regards Tim

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You can design without engineering, but you cannot engineer without design.
Using Win 10 with Designer 2016/2017 and TurboCAD Pro. Plat. 2018/2019 + Lightworks (64-bit versions) + AnimationLab 5.2.
Windows 10 Pro 1903 (Build 18362.476) 64-bit


March 13, 2014, 08:29:17 AM
#5

Hi Alvin,

it may help to read this . . .

http://www.andrewdaceyphotography.com/articles/dpi/

 . . . and similar articles, or, it may not!  :-\

Regards Tim

Yes, that did help Tim.  The first three paragraphs-- not so much (pretty rudimentary); but the paragraphs on PPI re-sizing and re-sampling, and the last section on DPI, did help me gain a better understanding of what is happening when I manipulate Images in IrfanView or a similar application.

Thanks for the link!  -Alvin

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Alvin Gregorio
(mostly Residential Architectural 2D; no formal CAD Training; intermittent TurboCAD user since yr. 2000 [ver6.5])
---TurboCAD: V21PP; V20.2PP; V19DL; V11.2Pro; Windows-7-Pro/64-bit; Intel-Core-i3 CPU; 2.27ghz; 4GB RAM; Intel HD Graphics (CPU based)


March 13, 2014, 08:33:58 AM
#6
I'm certainly no expert on this subject, but...

Thanks for the information and education Don.

Re-reading your Post after reading through the Link Tim provided, it's making sense to me (knowing what I didn't know before, but was utilizing).

This should help me in my future work, including Image manipulation choices, greatly in the future.

Thanks Don!  -Alvin

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Alvin Gregorio
(mostly Residential Architectural 2D; no formal CAD Training; intermittent TurboCAD user since yr. 2000 [ver6.5])
---TurboCAD: V21PP; V20.2PP; V19DL; V11.2Pro; Windows-7-Pro/64-bit; Intel-Core-i3 CPU; 2.27ghz; 4GB RAM; Intel HD Graphics (CPU based)


* March 15, 2014, 01:01:30 PM
#7
Hello Alvin and other TC'ers...!!!

I believe you already determined that resampling your capture from 96 dpi to 300dpi is not improving the quality, just bloating the file size.  When it comes down to it any change to an original image degrades the quality.  With that said, a loss in quality does not necessarily mean changes cannot be an improvement in viewing perception :)

I'll avoid getting long winded here and get right to the best method for you to accomplish your purpose.  When you capture the Google satellite image of the target parcel, zoom in as far as Google will let you and still have a satellite image.  Capture it at that zoom level.  If the parcel is larger than that zoom level will permit on your screen, do several captures to get the entire area of interest.  If several captures are required, you'll need a stitching or panorama image editor (uncertain if IrfanView has that feature), or some image editor which permits aligning the captures and saving as a single image.  Short of that, you can insert the captures individually in TC and align the images as best you can.

Essentially you to capture at the highest possible resolution and only size the image, not resample  it.  When you output to a specific size in the PDF, the PDF software will do any required resampling to the resolution in its settings (should be at least 300dpi for printed documents).  This will give you the best resolution that can be obtained given the starting image source.

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March 16, 2014, 07:11:58 AM
#8
Hello Alvin and other TC'ers...!!!

I believe you already determined that resampling your capture from 96 dpi to 300dpi is not improving the quality, just bloating the file size.  When it comes down to it any change to an original image degrades the quality.  With that said, a loss in quality does not necessarily mean changes cannot be an improvement in viewing perception :)

I'll avoid getting long winded here and get right to the best method for you to accomplish your purpose.  When you capture the Google satellite image of the target parcel, zoom in as far as Google will let you and still have a satellite image.  Capture it at that zoom level.  If the parcel is larger than that zoom level will permit on your screen, do several captures to get the entire area of interest.  If several captures are required, you'll need a stitching or panorama image editor (uncertain if IrfanView has that feature), or some image editor which permits aligning the captures and saving as a single image.  Short of that, you can insert the captures individually in TC and align the images as best you can.

Essentially you to capture at the highest possible resolution and only size the image, not resample  it.  When you output to a specific size in the PDF, the PDF software will do any required resampling to the resolution in its settings (should be at least 300dpi for printed documents).  This will give you the best resolution that can be obtained given the starting image source.

THANK YOU for the information and furthered education on the subject jhren.

An idea came to mind as I was re-reading your suggestions:

Since my (only) computer is a 17.3" 1600x900 laptop, and I usually use a 27" 1920x1080 second-monitor (lower PPI than the laptop screen), and most of the city and suburban single-family-residential lots (parcels) in my community are "deeper" than they are wide... after getting the Satellite view on my laptop screen (for the higher PPI), I can zoom in on that lot, then rotate my screen-view and zoom in optimally, before doing the screen-capture.
  Most of the lots in my area are close to a 16:9 ratio, depth-to-width.
I'll have to give that a try on my next project... as the "starting point" for creating/Inserting these satellite-images into TurboCAD.

Thanks, Alvin

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Alvin Gregorio
(mostly Residential Architectural 2D; no formal CAD Training; intermittent TurboCAD user since yr. 2000 [ver6.5])
---TurboCAD: V21PP; V20.2PP; V19DL; V11.2Pro; Windows-7-Pro/64-bit; Intel-Core-i3 CPU; 2.27ghz; 4GB RAM; Intel HD Graphics (CPU based)


* March 16, 2014, 10:12:06 AM
#9
Alvin,

I can see you still have some misconception about how images and resolution work on computer screens with respect to internet images and screen captures.  The physical dimensions of your screens play no part in capture resolution.  Only the zoom level of the satellite image and pixel count matter.  At max zoom of Google satellite image, the resolution with respect to the satellite image will be at best possible... and the same on either display... but you will be able to see/capture a few more pixels of the satellite image on the 1920x1080 display because it has a higher pixel count.

Now if your displays are connected to the same computer, you can "extend your desktop" to both screens and stretch the browser window across both displays for even greater pixel count. See attached image as an example.  Captured from two 1920x1080 displays.  Originally saved as png for quality.  Had to save as jpg to get under the 4k limit on file size upload... which reduces the image quality.  Also note this is at the max zoom permitted in IE for the area I captured (about 20 ft per "inch", i.e. 96 pixels; see scale at bottom right corner).

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March 16, 2014, 10:38:53 AM
#10
Alvin,

I can see you still have some misconception about how images and resolution work on computer screens with respect to internet images and screen captures.  The physical dimensions of your screens play no part in capture resolution.  Only the zoom level of the satellite image and pixel count matter.  At max zoom of Google satellite image, the resolution with respect to the satellite image will be at best possible... and the same on either display... but you will be able to see/capture a few more pixels of the satellite image on the 1920x1080 display because it has a higher pixel count.

Now if your displays are connected to the same computer, you can "extend your desktop" to both screens and stretch the browser window across both displays for even greater pixel count. See attached image as an example.  Captured from two 1920x1080 displays.  Originally saved as png for quality.  Had to save as jpg to get under the 4k limit on file size upload... which reduces the image quality.  Also note this is at the max zoom permitted in IE for the area I captured (about 20 ft per "inch", i.e. 96 pixels; see scale at bottom right corner).

Okay.  Now I "see" it:
    Though my thinking was correct that my laptop (17.3"; 1600x900) has a few more PixelsPerInch than my secondary monitor (27"; 1920x1080), when the Browser Image is zoomed such that the portion of the satellite image I wish to screen-capture has taken up the maximum amount of the screen, it's the 1920x1080 screen that will "populate" the screen-capture image with the most pixels.
    And if I Extend my displays I get even more "Pixel real estate".

But, my other comment was correct wasn't it?:
    If my "typical" house lot is "deeper" than it is wide-- approximately a 16:9 ratio as such-- then-- if I am limiting to only one screen-- my rotating my screen-view (CTRL+ALT+ArrowKeys on my system) when zooming, I am getting the most Pixel population in my screen-capture image.
   Right?   (I guess that depends on the lot's (parcel's) north/south/east/west orientation on my screen when viewing the satellite-view in a browser or Google Earth)

Thanks, Alvin
« Last Edit: March 16, 2014, 04:19:52 PM by Alvin Gregorio »

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Alvin Gregorio
(mostly Residential Architectural 2D; no formal CAD Training; intermittent TurboCAD user since yr. 2000 [ver6.5])
---TurboCAD: V21PP; V20.2PP; V19DL; V11.2Pro; Windows-7-Pro/64-bit; Intel-Core-i3 CPU; 2.27ghz; 4GB RAM; Intel HD Graphics (CPU based)


* March 16, 2014, 11:19:00 AM
#11
Right.

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March 16, 2014, 11:20:28 AM
#12
Right.

"Right".  That's what I like reading!

Thanks for your effort and help on this subject jhren!  -Alvin

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Alvin Gregorio
(mostly Residential Architectural 2D; no formal CAD Training; intermittent TurboCAD user since yr. 2000 [ver6.5])
---TurboCAD: V21PP; V20.2PP; V19DL; V11.2Pro; Windows-7-Pro/64-bit; Intel-Core-i3 CPU; 2.27ghz; 4GB RAM; Intel HD Graphics (CPU based)


* March 16, 2014, 03:17:36 PM
#13
Your welcome...!!!

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* March 16, 2014, 07:04:00 PM
#14
Greetings, Joe, haven't seen you around in a while.  Thanks for this info.

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* March 16, 2014, 07:20:33 PM
#15
If memory serves, Joe is the guy who taught us how to make a skillion Roof. Up to that point, I'd thought a "skillion" was a thousand jillion.

Henry H

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* March 16, 2014, 08:24:00 PM
#16
Greetings, Joe, haven't seen you around in a while.  ...
Hi, Murray.

Good to see you and some other TC die hards are still around... :)

My career has taken me into a non-CAD related area, so I seldom get a chance to exercise my TC abilities.

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* March 16, 2014, 08:28:33 PM
#17
If memory serves, Joe is the guy who taught us how to make a skillion Roof. Up to that point, I'd thought a "skillion" was a thousand jillion.

Henry H
Hello, Henry.

I seem to recall something about figuring out how to model a single slope roof with the roof tool... but I'll not take credit for realizing they are called a skillion roof... ;)

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