Test Report. Executive Summary. January 2006 Update: April For Epson America, Inc. Optical Density E. Evaluation of of 12 Scanners.

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1 January 2006 Update: April 2006 For Epson America, Inc. Optical Density E Evaluation of of 12 Scanners Inside: Executive Summary Epson America, Inc. contracted with to evaluate the Optical Density () of different scanners. followed the methodology described in ISO 21550, an internationally recognized standard that specifies methods for measuring the ability of scanners to capture tones especially in the dark areas of the original. A 41 step Stouffer Transparent Step Wedge, T4110 was used as the test chart to evaluate the. An optical density of at least 3.0 is recommended for film scanning. Hence, the scan area was chosen from step 31 to 41 with their density ranging from 3.0 to 4.0 respectively. On each scanner, the target was scanned at the maximum optical resolution of that scanner as specified by the manufacturer. Test Methodology The following 12 scanners were tested for : Epson Perfection 4990 Test Environment Photo, Epson Perfection 4490 Photo, Epson Perfection 3490 Photo, Epson Test Results Perfection V700 Photo, Canon CanoScan 9950F, Canon CanoScan 8400F, About Canon CanoScan 4200F, HP ScanJet 4370, HP ScanJet 4850, HP ScanJet 4890, Microtek ScanMaker i900 and Microtek ScanMaker 9800XL. The overall results of s tests show that the Epson scanners outperform each of the tested competitors and provided the highest optical density. The test results also reveal the Epson scanners as having more consistent values over the test scans (i.e. for each test iteration). observed in its series of tests that highest value for HP scanners was 3.1, compared to the >4.0 value measured for the Epson 4490 Photo, Epson 4990 Photo and Epson V700 Photo. Amongst the Canon scanners, the maximum for CanoScan 9950F was close to 3.0 but the maximum for CanoScan 4200F and CanoScan 8400F were found to be less than 3.0. The maximum for the Microtek scanners, ScanMaker i900 and ScanMaker 9800XL were also observed to be less than 3.0. NOTE: The Epson Perfection V700 Photo was tested in the last week of March 2006 and rest of the scanners were tested in Jan 2006.

2 Test Methodology followed the methodology described in ISO using Adobe Photoshop CS2 and a Stouffer T4110, (41 Step Transmission Guide 1" x 9") test chart. A Microsoft Excel spreadsheet was created implementing the formulas in ISO to populate the data and calculate the Optical Density. The test methodology involved 3 phases: 1. Scan Images 2. Process Images 3. Populate the Excel spreadsheet for computing Scan Images All the images were scanned with the following configuration: Scanning Mode: Professional Document Type: Film or Film with Holder Film Type: Positive Film Resolution: Maximum optical resolution of the scanner Unsharp Mask Filter: ON Auto Exposure: ON The step chart T4110 was placed onto the film holder. Strips of black insulation tape were used to cover the unused areas on the film holder. The film holder was placed on a scan bed to do a preview scan. On the preview image, the steps from 31 to 41 were selected and scanned. The scanned images were saved in TIFF format. After scanning an image, the interface was closed and the scanner was powered off. The scanner was switched on after 5 minutes to scan another image. The cold cathode lamps used in scanners can vary in their brightness from the moment they are turned on and they generally are brightest when first powered on. Hence, followed this procedure to ensure that the lamp will always be at its brightest for each scan. This procedure was repeated to obtain 10 sets of T4110 chart scanned images. Page 2

3 Process Images The following seven images were derived from this original image in order to evaluate the. 1. Luminance Image This is the original image itself with RGB channels The Channels window was opened in the Photoshop by selecting channels in the Window task bar. Using the Split Channels function on the Channels tab, the original image was split into R, G and B channels and saved as R.psd, G.psd and B.psd respectively to obtain R, B and G images 2. R Image 3. G Image 4. B Image The Lab Channels are opened by selecting Lab Color for Mode on the Image task bar. Using the Split Channels function, the original image was split into lab channels L, a and b. The L channel was saved as L.psd to obtain the L image while discarding the a and b channels. 5. L Image The Calculations window is opened by selecting Calculations from the Image task bar. The R image was subtracted from the L image by selecting following options from the drop down menu on the Calculations window to obtain R-L image 6. R-L Image Source 1: L.psd Source 2: R.psd Layer: Background Channel: Gray Blending: Subtract Result: New Document The B image was subtracted from the L image using the same procedure mentioned above to obtain 7. B-L Image Page 3

4 Populate the Excel Sheet The image was opened using Adobe Photoshop CS2. Steps of different tones of black could be seen for the image, but the boundary between each step may not be seen clearly. Thus, guidelines were created for each step of chart image using the rulers. The Rulers were selected from View on the taskbar. The Navigator value was set to 80 to in order to view one complete step on the screen. The Style for marquee area was selected as Fixed Size with dimension 1mm x 1mm. The marquee area was aligned to the center of each step bounded by guidelines. The histogram function of the Photoshop was used to obtain the values for Standard Deviation and Mean for the marked area of the image. These steps were followed for all the images and the Excel spreadsheet was populated accordingly. A Microsoft Excel sheet was created implementing the formulas in ISO to compute the. After populating the Excel spreadsheet with Average (Mean) values for R-Image, G-Image and B- Image and the Standard Deviation values for R-Image, G-Image, B-Image, R-L mage, B-L Image, L Image and Luminance image, the Excel spreadsheet automatically calculated the OECF value for Luminance image using the following formula as specified by the ISO 21550: Y (i) = x R (i) x G (i) x B (i) For monochrome scans Y (i) shall be equivalent to the single band data. i = Number of grey patch Y= Visually weighted output signal The Transmission of a density patch is calculated using the formula: T(i) = 10 -D(i) The incremental gain is determined from the Scanner OECF as follows: g(i) = Y(i) -Y(i +1) T(i) -T(i +1) + Y(i -1) -Y(i) /2 for i min < i < i max T(i -1) -T(i) g(i min ) = Y(i) -Y(i +1) T(i) -T(i +1) g(i max ) = Y(i -1) -Y(i) T(i -1) -T(i) g(i) = incremental gain of patch i Y(i) = Visually weighted average count level of patch i Page 4

5 T(i) = Transmission level of patch i i = number of grey patch with i min as lightest and i max as darkest patch The Standard Deviation σ is calculated as below: σ(i) = [σ(y) ² σ(r-y) ² σ(b-y) ²] 1/2 The values for Incremental gain, Transmission and Standard Deviation are substituted in the below formula to find the Signal to Noise Ratio (): S/Nx(i) = T(i) g(i) σ(i) The Optical Density value before the Signal to Noise Ratio drops below 1 will be the maximum Optical Density detected from that scanned image. These steps were followed for all the Step Chart T4110 scanned images and tabulated a max value from each chart image with a new Excel spreadsheet. The Max of scanner is determined by computing the average of max values obtained from all 10 chart images. Page 5

6 Test Environment All scanners were connected by USB to a HP Compaq dc7100 SFF with a Intel Pentium 4, 3.0 GHz processor, 1GB of RAM, an Intel 82915G/GV/910GL chipset display adapter and Windows XP Professional with Service Pack 2. Screen resolution was set at 1280x1024 with 32-bit color. Images were viewed on a HP 1702 monitor, with.264 mm (H) dot pitch and.264 mm (W) dot pitch. The images were scanned into Adobe Photoshop CS2. A clean disk image with Windows XP Professional, Service Pack 2, and Photoshop CS2 was installed before a new scanner was tested in order to eliminate any problems with Twain drivers of previously tested scanners. The Twain drivers used: HP Image Zone Software Version 5.3 for HP Scanjet 4370, HP Scanjet 4850 and HP Scanjet 4890 EPSON Scan v2.71a for EPSON Perfection 3490 Photo and EPSON Perfection 4490 Photo EPSON Scan v2.80a for EPSON Perfection V700 Photo Microtek ScanWizard Pro v6.13 for Microtek ScanMaker 9800XL Microtek ScanWizard Pro for Microtek ScanMaker i900 ScanGear CS v1.01 for CanoScan 4200F ScanGear CS v1.02 for CanoScan 8400F and for CanoScan 9950F Stouffer Transparent Step Wedge T4110 was used as the test chart. The test chart and its specifications can be found below: Page 6

7 Step Target Tolerance % Light Transmission na na na na na na na na na na *.05film base is assumed to have 100% transmission. Page 7

8 Test Results The test results have been summarized in this section of the report. The scope of the tests was limited to evaluate the maximum of scanners in the range of 3.0 to 4.0. Hence, does not provide an analysis of the actual values for scanners if it was found to be below 3.0 or above 4.0. The for each step of the scanned image is computed as described in the methodology section of this report. The for each step of the test chart T4110 is specified by its manufacturer. The value obtained for each step of the image and its corresponding known value along with the step number is tabulated as shown below. The Optical Density value before the Signal to Noise Ratio drops below 1 will be the maximum Optical Density detected for that scanned image. In the table below for Epson Perfection 3490 photo, the drops below 1 for step number 34 with a known of 3.3. Hence, the maximum of this scanner is 3.2 as it is the value before the drops below 1. A total of 10 images were scanned for each scanner and the values were evaluated for each image. completed 10 iterations of the test scans in order to provide more consistent results and to determine the reliability across scan events of the values. The reported maximum Optical Density of the scanner was determined by taking the average of the maximum values of the 10 scanned images. The following tables and graphs show the average and values obtained for each scanner. The detailed results for all the images can be found in the Excel files attached with this report. Excel files are named after the scanner. Each Excel file has 11 worksheets. Data from the processed images are entered into first 10 worksheets and the 11 th worksheet named Total is automatically calculated using the data from first 10 worksheets. Epson Perfection 3490 Photo EPSON Perfection 3490 Photo, Optical Resolution 3200 dpi, Positive Film scan, Unsharp Mask Filter ON, Autoexposure ON = 3.2 Page 8

9 Epson Perfection 3490 Photo yielded consistent values for each scan. Out of ten scanned images, eight of them were observed to have a maximum of 3.2, one reported a value of 3.1 and the other 3.3 with an average maximum of 3.2. Epson Perfection 4490 Photo EPSON Perfection 4490 Photo, Optical Resolution 4800 dpi, Positive Film scan, Unsharp Mask Filter ON, Autoexposure ON The values for all the 10 scanned images for Epson Perfection 4490 Photo scanner were found to be greater than one. Since, it was not in the scope of the tests to find out the exact value above 4.0, does not specify the exact number for this scanner. The standard deviation values for this scanner were observed to be high as compared to other Epson scanners that seemed to be the only concern with this scanner. Epson Perfection 4990 Photo EPSON Perfection 4990 Photo, Optical Resolution 4800 dpi, Positive Film scan, Unsharp Mask Filter ON, Autoexposure ON The values for all the 10 scanned images for Epson Perfection 4990 Photo scanner were found to be greater than one. Since, it was not in the scope of the tests to find out the exact value above 4.0, does not specify the exact number for this scanner. observes from these measurements that the average maximum value for this scanner is greater than 4.0. Page 9

10 Epson Perfection V700 Photo 6400 dpi Step No Optical Density Average EPSON Perfection V700 PHOTO, Optical Resolution 6400 dpi, Positive Film scan, Unsharp Mask Filter ON, Autoexposure ON 4800 dpi Positive Film scan, Unsharp Mask Filter ON, Autoexposure ON EPSON Perfection V700 PHOTO, Optical Resolution 4800 dpi, Epson Perfection V700 Photo was tested at both 6400 dpi and 4800 dpi resolutions. This scanner yielded consistent values for each scan at both the resolutions. The values for all the scanned images for Epson Perfection V700 Photo scanner were found to be greater than one. observes from these measurements that the average maximum value for this scanner is greater than 4.0. Page 10

11 HP ScanJet HP ScanJet 4850, Optical Resolution 4800 dpi, Positive Film scan, Unsharp Mask Filter ON, Autoexposure ON = 3.1 The maximum values for HP ScanJet 4850 were found to be spread out from less than 3.0 to 3.3 for our 10 test scans. Out of the ten scanned images, one image reported an of 3.3, four of them reported an of 3.2, three reported 3.1, and one reported 3.0 and two values less than 3.0. The average maximum was found to be 3.1. HP ScanJet 4370 NOTE: The average maximum value for this scanner was observed to be less than 3.0. Hence, it is not reported. However, 4 out of 10 test images did report a maximum above 3.0. The table and the graph below are the and values of one test image that reported a maximum of 3.0. Step No Optical Density HP ScanJet 4370, Optical Resolution 3600 dpi, Positive Film scan, Unsharp Mask Filter ON, Autoexposure ON = Page 11

12 The maximum values for HP ScanJet 4370 were spread out from less than 3.0 to 3.1. One image reported an of 3.1, three images reported 3.0 while the rest reported less than 3.0. The maximum value for Canon CanoScan 9950F, Canon CanoScan 8400F, Canon CanoScan 4200F, HP ScanJet 4890, Microtek ScanMaker i900 and Microtek ScanMaker 9800XL were found to be less than 3.0. The following tables and graphs show the average and values obtained for the above mentioned scanners with less than 3.0. Canon CanoScan 9950F Canon CanoScan 9950F, Optical Resolution 4800 dpi, Positive Film scan, Unsharp Mask Filter ON, Autoexposure ON Canon CanoScan 8400F Canon CanoScan 8400F, Optical Resolution 3200 dpi, Positive Film scan, Unsharp Mask Filter ON, Autoexposure ON Page 12

13 Canon CanoScan 4200F Canon CanoScan 4200F, Optical Resolution 3200 dpi, Positive Film scan, Unsharp Mask Filter ON, Autoexposure ON HP ScanJet 4890 The Standard Deviation values obtained from the histogram function of the Photoshop for all the marked areas of R and G images were found to be 0 while scanned at 4800 dpi. Hence, the optical density could not be computed for images scanned at 4800 dpi [Refer Page 5 of Test Methodology section]. The test was repeated by scanning the test image at lower resolutions. The table below the shows the average values for this scanner at 1200 dpi HP ScanJet 4890, Optical Resolution 1200 dpi, Positive Film scan, Unsharp Mask Filter ON, Autoexposure ON Page 13

14 Microtek ScanMaker i Microtek ScanMaker i900, Optical Resolution 3200 dpi, Positive Film scan, Unsharp Mask Filter ON, Autoexposure ON Microtek ScanMaker 9800XL Microtek ScanMaker 9800XL, Optical Resolution 1600 dpi, Positive Film scan, Unsharp Mask Filter ON, Autoexposure ON Page 14

15 The following table summarizes the test results for all the 12 scanners. Scanner Optical Resolution Maximum Optical Density Epson Perfection 3490 Photo Epson Perfection 4490 Photo 4800 More than 4.0 Epson Perfection 4990 Photo 4800 More than 4.0 Epson Perfection V700 Photo 6400/4800 More than 4.0 Canon CanoScan 4200F 3200 Less than 3.0 Canon CanoScan 8400F 3200 Less than 3.0 Canon CanoScan 9950F 4800 Less than 3.0 HP ScanJet Less than 3.0 HP ScanJet HP ScanJet Less than 3.0 Microtek ScanMaker i Less than 3.0 Microtek ScanMaker 9800 XL 1600 Less than 3.0 Page 15

16 About is the leading independent information technology testing organization for the computer industry, dedicated to providing high quality services and test tools to hardware developers, software publishers, government agencies and corporations. has extensive experience developing and conducting objective tests to assess new and existing products for compatibility, performance, comparative performance, usability, and functionality. Our testing services are also used for capacity planning, acquisition support and impact analysis. s proficiency and thoroughness provide clients with a high quality, costeffective means to assess, differentiate and evaluate IT products. Additional information about is available through the World Wide Web at. For further information about, please contact us at: Telephone: Fax: info@nstl.com, Inc. prepared this report under contract for Epson America Inc. does not guarantee the accuracy, adequacy or completeness of the services provided to Epson or the data included herein. MAKES NO WARRANTIES, EXPRESS OR IMPLIED, AS TO RESULTS TO BE OBTAINED BY ANY PERSON OR ENTITY FROM USE OF THE CONTENTS OF THIS REPORT. MAKES NO EXPRESS OR IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE OF ANY PRUCT MENTIONED IN THIS REPORT. Page 16